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Part  I.  (First  Fascicle)  INTRODUCTION  AND 
PROTOZOA.  By  Sir  RAY  LANKESTER,  K.C.B.,  F.R.S.  ; 
Prof.  S.  J.  HICKSON,  M.A.,  F.R.S.  ;  F.  W.  GAMBLE, 
D.Sc.,  F.R.S.  ;  A.  WILLEY,  M.  A.,  D.Sc., T.R.S.  ;  J.  J. 
LISTER,  F.R.S.  ;  H.  M.  WOODCOCK,  D.Sc. ;  and  the  late 
Prof.  WELDOK. 

Part  I.  (Second  Fascicle)  INTRODUCTION  AND 
PROTOZOA.  By  J.  B.  FARMER,  D.Sc.,  M.A.,  F.R.S.  ; 
J.  J.  LISTER,  F.R.S.  ;  E.  A.  MINCHIN,  M.A.  ;  and  S.  Jv 


By  Sir  RAY  LANKESTER,  K.C.B.,  F.R.S. ;  E.  A.  MINCHIX, 
M.A. ;  G.  HERBERT  FOWLER,  B.A.,  Ph.D.  ;  and  GILBERT 
C.  BOURNE,  M.A. 

M.A.,  assisted  by  J.  W.  GREGORY,  D.Sc.,  and  E.  S. 

and  THE  NEMERTINI.  By  Prof.  BENHAM,  D.Sc. 

Part  V.   MOLLUSCA.     By  Dr.  PAUL  PILSENEEH. 
Part  VII.   CRUSTACEA.     By  W.  T.  CALMAX. 

Part    IX.  VERTEBRATA   CRANIATA.     By  E.   s. 






K.C.B.,  M.A.,  LL.D.,  F.R.S. 








S.  J.   HICKSON,  F.R.S. 


J.  J.   LISTER,  F.R.S. 


F.   W.  GAMBLE,  D.Sc.,  F.R.S. 


A.  WILLEY,  M.A.,  D.Sc.,  F.R.S. 


H.  M.  WOODCOCK,  D.Sc. 


THE  LATE  W.  F.  R.  WELDON,  F.R.S. 



E.   RAY  LANKESTER,  K.C.B.,  F.R.S. 







64  &  60  FIFTH  AVENUE,  NEW  YORK 




INDIA  .    .    .     MACMILLAN  &  COMPANY,  LTD. 




THE  two  fascicles  of  the  first  part  of  this  treatise  give  a  more 
complete  account  of  the  Protozoa  than  is  to  be  found  in  any 
similar  work  hitherto  published.  Especial  attention  has  been 
given  to  the  treatment  of  those  groups  —  the  Sporozoar 
Flagellata,  and  Hsemoflagellata — which  have  recently  acquired 
so  much  importance  in  consequence  of  the  discovery  that  some 
of  their  constituent  members  are  the  causes  of  important 
diseases  in  man  and  animals. 


December  1908. 






„        B. — THE  HELIOZOA  .                  ....  14 

,,        C. — THE  MYCETOZOA        .         .        .        .        .  37 

„        D. — THE  LOBOSA      ......  68 

„        E. — THE  RADIOLARIA 94 

„        F. — THE  MASTIGOPHORA    .                  ...  154 

n       G. — THE      HAEMOFLAGELLATES     AND      ALLIED 

FORMS  .        .        .         .        .         .         .193 


„           B. — THE  XENOPHYOPHORIDAE     .         .        .  284 

INDEX  287 

vii  b  ' 



THERE  are  certain  matters  which  require  brief  treatment  by  way 
of  introduction  to  the  present  treatise  on  Zoology. 

The  first  concerns  the  limitation  of  the  subject-matter  indicated 
by  the  term  "  Zoology,"  requiring  a  statement  of  what  living  things 
are  here  considered  as  animals  and  what  are  excluded  from  that 
title.  The  second  concerns  the  grouping  of  animals  in  large  series 
corresponding  to  the  indications  afforded  by  their  structure  as  to 
their  genetic  affinities.  The  method  adopted  in  the  present  work 
has  been  to  take  large  divisions  of  the  Animal  series  such  as  are 
often  called  "  sub-kingdoms  "  or  "  phyla  "  (or  in  some  instances  less 
comprehensive  divisions)  one  by  one  for  systematic  description  and 
for  more  detailed  enumeration  and  justification  of  the  classes,  orders, 
and  families  recognised  than  is  usual  in  handbooks  of  Zoology. 
These  large  divisions  have  been  assigned  for  treatment  to  separate 
authors,  and  in  each  case  the  author  has  given  a  description  of  the 
characters  which  justify  the  recognition  of  the  group  which  he 
treats  as  an  independent  series ;  to  this  he  has  added  a  more 
extended  discussion  of  the  range  of  variety  in  the  structure  of  the 
forms  held  to  be  reasonably  considered  as  members  of  the  series. 

A  special  chapter  written  by  me  forms  the  introduction  to 
volume  ii.  of  this  work.  It  may  be  regarded  as  a  continuation  of 
the  present  chapter,  and  treats  of  the  division  of  the  higher  grade 
of  animals,  which  is  called  the  Metazoa  (the  lower  being  the 
Protozoa),  into  two  branches,  the  "  Parazoa  "  and  the  "  Enterozoa." 
It  is,  however,  chiefly  occupied  with  a  discussion  of  the  division 
of  the  Enterozoa  into  two  grades  of  higher  and  lower  structural 
complexity,  which  are  designated  respectively  the  "  Enterocoela " 
and  "  Coelomocoela."  The  chief  phyla  or  large  branches  of  the 
animal  pedigree  are  there  enumerated,  whilst  each  is  subsequently 
treated  by  independent  authors. 

In  the  present  introductory  chapter  I  have  therefore  to  consider, 
besides  the  question  as  to  what  distinctions  separate  animals  from 

1  By  Sir  Ray  Laukester,  K.C.B. 



other  living  things,  the  facts  which  render  it  necessary  to  recognise 
two  great  primary  grades  of  animals — a  lower  called  the  Protozoa 
and  a  higher  called  the  Metazoa. 


Living  things — Bionta — are  without  difficulty,  and  by  the 
general  agreement  of  both  skilled  naturalists  and  the  observant 
layman,  divided  into  two  greatly  differing  groups  or  series,  the 
animals  or  Zoa  and  the  plants  or  Phyta,  and  into  those  two  great 
groups  only.  The  study  of  the  one  series  is  called  Zoology,  and  of 
the  other  Phytology,  or  more  usually  Botany.  It  is  easy  to  lay 
down  certain  general  propositions  by  which  nearly  all  animals  are 
distinguished  from  nearly  all  plants.  The  distinctions  which  can 
be  thus  indicated  all  arise  from  one  great  difference  in  the  chemical 
activity  of  the  living  substance  of  an  animal  as  compared  with  that 
of  a  plant.  Although  the  living  substance  of  both  animals  and 
plants,  to  which  Hugo  von  Mohl  gave  the  name  Protoplasm,  appears 
in  both  series  in  the  form  of  nucleated  corpuscles  called  cells, 
and  although  the  formal  appearances  and  the  range  of  chemical 
activities  exhibited  both  by  the  general  protoplasm  and  by  the 
nuclear  structures  of  the  cells  of  animals  and  plants  are  practically 
identical,  yet  there  is  a  predominant  difference  in  the  habitual 
exhibition  of  their  activities  which  separates  animals  from  plants, 
and  has  determined  the  difference  of  form  and  activity  characteristic 
of  the  living  things  assigned  to  either  of  the  two  groups. 

Living  protoplasm,  whether  of  animal  or  plant,  undergoes 
(when  the  processes  of  life  are  not,  as  they  may  be  for  a  short  or 
for  a  very  extended  period,  suspended)  constant  chemical  change, 
requiring  the  access  of  free  oxygen  to  the  protoplasm  and  the 
consequent  oxydation  of  some  of  its  material — which  becomes 
"  wasted "  or  lost  and  carried  away  by  diffusion  from  the  living 
protoplasm.  This  loss  has  to  be  replaced,  and  the  process  by  which 
it  is  replaced  is  "  nutrition  " ;  the  material  taken  by  a  living  thing 
for  the  purposes  of  nutrition  is  its  "food." 

The  result  of  nutrition  is  not  limited  to  the  repair  of  loss  in 
the  living  thing,  but  is  for  a  part  or  the  whole  of  its  existence 
in  excess  of  the  loss ;  so  that  increase  of  the  bulk  of  the  living 
material  or  "growth"  is  a  result.  The  elements  carbon,  hydrogen, 
oxygen,  and  nitrogen,  combined  to  form  molecules  of  the  highest 
degree  of  complexity,  are  the  essential  constituents  of  living 
material.  It  is  these  that  are  oxydised  and  wasted  and  pass  from 
the  living  thing  during  life  :  it  is  these  which  have  to  be  replaced. 

Animals  are  unable  to  assimilate,  that  is,  to  utilise  as  food,  the 
simpler  chemical  compounds  of  carbon  or  of  nitrogen.  They  can 
only  take  their  nitrogen  from  food  which  is  in  the  elaborate  form  of 


combination  which  is  called  a  proteid ;  they  can  only  take  their  carbon 
either  from  a  proteid  or  from  a  carbohydrate  or  a  hydrocarbon. 

These  elaborate  compounds  only  occur  in  the  bodies  of  other 
animals  or  of  plants.  Hence  animals  absolutely  depend  for  their 
food  on  other  living  things.  Plants,  on  the  contrary,  are  (with 
certain  exceptions)  able  to  take  up  as  food  the  compounds  of  carbon 
and  of  nitrogen  which  may  be  called  the  stable  or  resting  condition 
of  those  elements — namely,  the  simple  oxide  of  carbon — carbonic 
acid  gas  and  the  simple  compound  of  nitrogen  with  hydrogen  which 
is  called  ammonia,  or  the  oxide  of  nitrogen  which  forms  nitrates. 
This  "  food  "  of  plants  is  diffused  throughout  the  earth's  surface  in 
air  and  water;  hence  they  need  to  expose  a  large  absorbing  surface 
to  those  media ;  hence  their  branches  and  leaves  spread  in  tree- 
like form  to  the  air  or  to  the  water,  whilst  their  roots  are  spread  to 
the  water  contained  in  the  soil.  Their  food  is  ever  moving  and 
flowing  around  them  :  they  have  neither  to  move  in  search  of  it 
nor  to  seize  it.  Hence  the  majority  of  plants  are  fixed  and  find 
safety  and  protection  in  stability.  Animals,  on  the  other  hand,  have 
to  obtain  their  food  from  the  scattered,  solid,  separate  bodies  of 
plants  or  of  other  animals.  They  have  to  move  in  search  of  it,  they 
have  to  seize  it  when  found,  and  they  have  to  act  chemically  on 
the  solid  or  viscous  body  or  fragment  of  their  prey  so  as  to  dis- 
solve it  and  to  enable  the  dissolved  material  containing  the  precious 
carbon  and  nitrogen  in  a  high  state  of  chemical  combination  to 
diffuse  into  their  living  substance  and  there  be  further  assimilated 
and  built  up  into  the  material  of  protoplasm.  For  these  purposes 
animals  possess  structures  enabling  them  to  move  more  or  less 
rapidly,  and  others  enabling  them  to  seize  or  grasp.  Further,  and 
of  even  more  fundamental  a  character  as  determining  their  whole 
shape  and  organisation,  they  possess  (with  rare  and  intelligible 
exceptions)  an  aperture,  the  month,  leading  into  a  relatively  extensive 
cavity,  the  gut,  into  which  the  solid  or  viscous  mass  of  food  is  intro- 
duced, and  when  there  is  chemically  dissolved  or  "  digested." 

The  obvious  and  predominant  difference  in  the  make  and  habit 
of  plants  as  compared  with  animals  is  thus  connected  with  the  very 
great  and  definite  difference  in  the  nature  of  the  food  of  the  two 

These  statements  are  true  in  a  general  way,  but  require 
qualification.  In  the  first  place,  we  find  it  necessary  to  regard  as 
genetically  part  of  the  great  Plant  series  many  organisms  which  are 
not  able  to  procure  their  carbon  from  carbonic  acid  nor  their  nitro- 
gen from  ammonia.  Only  the  green  plants  are  able  to  perform  this 
constructive  feat.  The  protoplasm  of  the  more  superficial  cells  of 
green  plants  contains  corpuscles  impregnated  with  a  transparent 
green  matter  known  as  chlorophyll.  In  the  presence  of  and  in 
virtue  of  the  physical  action  of  sunlight  screened  by  their  chloro- 


phyll,  the  protoplasm  of  these  cells  has  the  property  of  decompos- 
ing carbonic  acid,  liberating  free  oxygen,  and  combining  the  carbon 
with  hydrogen  and  oxygen  to  form  starch.  This  is  the  critical  step 
in  the  interaction  of  chemical  elements  on  the  earth's  surface,  by 
which  life  is  at  present  determined.  Were  there  no  assimilation  of 
carbon  from  carbonic  acid  to  form  starch — by  the  green  plants — 
the  whole  fabric  of  the  living  world  would  tumble  to  the  ground — in 
truth,  become  mineralised.  All  living  matter  breaks  down,  within  a 
short  space  of  hours  or  days,  to  the  resting  or  mineral  condition  of 
carbonic  acid  and  ammonia  (or  nitrates).  Were  the  building-up 
process,  the  raising  to  higher  potentiality,  not  incessantly  performed 
by  green  plants — a  power  which  chlorophyll  and  chlorophyll  alone 
confers  on  them — all  carbon  must  pass  from  the  reach  of  the  organic 
world  and  living  matter  come  to  an  abrupt  end. 

And  this  is  equally  true  of  nitrogen.  The  nitrogen  present  in 
living  protoplasm  tends  inevitably  to  the  stable  inert  condition — as 
a  nitrate,  as  ammonia,  or  as  the  pure  dissociated  atmospheric  gas. 
It  is  only  by  a  subtle  chemical  process  which  occurs  in  the  green 
plant — as  a  result  of  and  in  connection  with  the  fixation  of  carbon 
as  starch — that  nitrogen  taken  up  in  water  by  the  roots  of  the  plant 
as  nitrate  and  as  ammonia  is  brought  into  combination  as  part  of  an 
"  organic  "  compound  or  molecule.  Thus  in  the  ultimate  history  of 
the  chemistry  of  living  things  the  animal  depends  for  its  necessary 
food — proteids,  carbohydrates,  and  hydrocarbons — on  chlorophyll, 
the  "  leaf-green  "  of  green  plants.  Vegetarian  animals  swallow 
and  digest  these  substances  built  up  by  plants  ;  carnivorous  animals 
swallow  and  digest  animals  which  have  already  profited  by  the 
work  of  the  green  plant.  No  animal  can  take  up  even  a  fraction 
of  a  grain  of  carbon  or  nitrogen  from  a  stomachful  of  carbonates, 
nitrates,  and  ammonia. 

There  are,  however,  as  exceptions  plants  which  are  devoid  of 
chlorophyll  and  depend  upon  the  results  of  the  constructive  activity 
of  other  plants  and  of  animals,  just  as  per  contra  there  are  ex- 
ceptional parasitic  animals  which  have  no  mouths  or  gut  and  live 
in  the  diffusible  nutritive  juices  elaborated  by  other  animals,  which 
they  absorb  by  the  surface  of  their  bodies.  The  chemical  life  of 
those  plants  which  are  devoid  of  chlorophyll — the  fungi,  the 
bacteria,  and  a  few  others — may  be  considered  as  corresponding  in 
character  to  that  of  those  tissues  or  cell-groups  of  green  plants 
which  lie  within  the  green  plant  and  are  devoid  themselves  of 
chlorophyll.  Both  these  tissues  and  the  autonomous  fungi  and  the 
saprophytes  depend  for  their  food  on  the  products  supplied  to 
them  by  the  chlorophyll-holding  cells  of  green  plants.  There  are 
minute  filamentous  and  rod-like  plants  devoid  of  chlorophyll 
(Bacteria  and  others)  which  can  take  their  carbon  as  tartaric  acid 
and  their  nitrogen  as  ammonia.  It  is  probable  that  all  such  non- 


chlorophylligerous  plants  must  be  regarded  as  derived  from  chloro- 
phyll-bearing ancestors — by  adaptation  to  a  food  already  somewhat 
raised  by  other  organisms  above  the  lowest  stage  of  carbon- 

Again,  there  are  amongst  the  most  highly  developed  flowering 
plants  examples  here  and  there  of  the  exceptional  and  special 
development  of  stomach-like  organs  with  mouth-like  openings  into 
which  insects  are  attracted,  and  when  once  entrapped  are  held 
either  by  the  actual  movement  of  a  grasping  organ  or  by  other 
mechanical  apparatus,  and  are  digested  by  chemical  secretions 
identical  in  character  with  those  of  the  animal  stomach,  the  digested 
product  being  absorbed  and  serving  to  nourish  the  plant.  Such 
cases,  whilst  they  demonstrate  in  a  most  striking  way  the  essential 
identity  of  the  faculties  of  the  living  protoplasm  of  plant  and 
animal,  do  not  invalidate  the  fundamental  proposition,  that  plants 
are  a  series  of  organisms  which  have  developed  their  distinctive 
form  and  structure  as  feeders  on  the  diffused  carbonic  acid,  ammonia, 
and  nitrates  of  the  circumambient  medium ;  whilst  animals  are  a 
series  which  have  developed  their  distinctive  form  and  structure 
as  feeders  on  scattered — often  elusive — live  or  dead  bodies  or  solid 
particles  of  other  animals  or  of  plants,  that  form  being  essentially  a 
locomotive  sac  with  a  mouth.  Amongst  the  larger  animals,  those 
visible  to  the  naked  eye,  there  are  few  exceptions  to  this  rule. 
Such  exceptions  are  found  in  the  obviously  exceptional  and  therefore 
aberrant  internal  parasites  which  require  no  mouth  nor  digestive  sac. 

But  there  are  a  few,  very  rare  cases  of  small  aquatic  animals 
which  are  provided  with  chlorophyll-corpuscles  and  obtain  a  part 
(in  one  case,  the  worm  Convoluta,  the  whole)  of  their  nutriment 
in  the  same  Avay  as  does  the  green  plant,  namely,  in  virtue  of  the 
assimilation  of  carbon  from  carbonic  acid  in  the  chlorophyll- 
bearing  tissue  when  under  the  influence  of  sunlight.  The 
chlorophyll-bearing  cells  of  the  worm  Convoluta  and  of  many 
Anthozoa  have  been  shown  to  be  unicellular  parasites  which  have 
established  the  closest  relationship  to  their  hosts.  But  it  is  by  no 
means  demonstrated  that  the  chlorophyll-corpuscles  of  Spongilla  and 
of  Hydra  are  parasitic  in  origin.1  The  fact  that  they  are  not 
chlorophyll-bearing  cells,  but  simple  non-nucleated  corpuscles  with 
a  cortex  impregnated  with  chlorophyll  precisely  comparable  to  the 
chlorophyll  corpuscles  of  green  plants,  does  not  permit  us  to 
consider  them  as  parasites  which  have  effected  a  lodgment  and 
association  with  Spongilla  and  Hydra  with  any  more  reason  than 
we  can  adduce  for  so  regarding  the  similar  corpuscles  in  green 
plants.  The  view  has  been  seriously  advanced  that  the  latter  are, 

1  See  on  this  subject  my  memoir  on  "The  Chlorophyll-corpuscles  and  Amyloid 
Deposits  of  Spongilla  and  Hydra"  in  vol.  xxii.  (1882)  of  the  Quart.  Journal  of 
Microsc.  Science. 


in  fact,  also  parasites.  This  may  prove  eventually  to  be  susceptible 
of  something  like  demonstration,  but  in  the  meantime  we  must 
ask  where  the  limit  to  this  assumption  that  chlorophyll  is  of 
parasitic  origin  is  to  be  placed. 

It  cannot  be  that  all  chlorophyll — even  that  observed  in  all  uni- 
cellular plants  and  animals — is  to  be  regarded  as  "  parasitic."  And 
if  we  are  once  able  to  distinguish  certain  independent  unicellular 
organisms  which  actually  manufacture  chlorophyll  Avithin  them- 
selves by  the  activity  of  their  own  protoplasm,  we  shall  be  able  to 
study  the  steps  of  that  process  and  to  judge  as  to  whether  the 
protoplasm  of  the  green  cells  of  green  plants  and  of  the  freshwater 
sponge  and  of  the  green  Hydra  do  or  do  not  form  chlorophyll 
plastids  in  the  same  way  and  in  virtue  of  the  same  protoplasmic 
capacity  as  do  minute  unicellular  algae. 

There  is  no  reason,  a  priori,  for  refusing  to  ascribe  to  a  tissue- 
cell  of  a  Sponge  or  a  Hydra  the  same  capacity  to  form  a  chemical 
deposit  of  any  kind  which  a  free  unicellular  organism  possesses. 
Unfortunately  this  is  not  a  case  in  which  the  simple  test  of  observa- 
tion can  be  applied,  so  that  the  question  as  to  whether  the  tissue- 
cell  does  construct  a  chlorophyll -corpuscle  or  does  not  can  be  settled 
by  inspection.  The  intricacies  of  structure  and  growth  are  in  this 
matter  such  as  to  render  direct  observation  difficult  and  illusive. 

Whilst  there  are,  then,  exceptional  cases  in  both  plants  and 
animals  as  to  the  great  nutritional  distinction  between  the  two 
series,  it  is  comparatively  easy  in  all  excepting  the  very  lowest 
forms  to  satisfy  ourselves  that  the  departures  from  the  rule  are 
specialised  derivatives  from  the  main  series.  The  colourless  or 
greenless  plants  are  descended  from  green  chlorophylligerous 
ancestors ;  mouthless,  gutless  animals  are  descended  from  mouth- 
bearing,  gut-hollow  animals. 

When,  however,  we  come  to  the  very  lowest  unicellular  micro- 
scopic forms  of  life,  there  is  greater  difficulty  in  assigning  some  of 
the  minuter  organisms  to  one  side  or  the  other,  and  to  some  extent 
our  decision  in  the  matter  must  depend  on  the  theory  we  may 
provisionally  adopt  as  to  the  nature  of  the  earliest  living  material, 
which  was  the  common  ancestral  matrix  from  which  both  the 
Plant  series  and  the  Animal  series  have  developed.  The  real 
question  in  regard  to  such  a  theory  is  as  to  whether  we  find 
reason  to  suppose  that  the  combination  of  carbon  and  nitrogen  to 
build  up  proteid,  and  so  protoplasm,  required,  in  the  earliest  state 
of  the  earth's  surface,  the  action  of  sunlight  and  the  chlorophyll 
screen.  We  must  remember  that,  though  these  are  now  necessary 
for  the  purpose  of  raising  carbon,  and  indirectly  nitrogen,  from  the 
mineral  resting  state  to  the  high  elaboration  of  the  organic  mole- 
cule, yet  it  is,  after  all,  living  protoplasm  which  effects  this  marvel 
with  their  assistance  ;  and  it  seems  (though  possibly  there  are  some 


who  would  deny  this)  that  it  is  protoplasm  which  has,  so  to  speak, 
invented  or  produced  chlorophyll.  Accordingly,  I  incline  to  the 
view  that  chlorophyll  as  we  now  know  it  is  a  definitely  later  evolu- 
tion— an  apparatus  to  which  protoplasm  attained,  and  as  a  conse- 
quence of  that  attainment  we  have  the  arborescent,  filamentous, 
foliaceous,  fixed  series  of  living  things  called  plants.  But  before 
protoplasm  possessed  chlorophyll  it  had  a  history.  It  had  in  the 
course  of  that  history  to  develop  the  nucleus  with  its  complex 
mechanism  of  chromosomes,  and  it  had  during  that  period  to 

The  suggestion  has  been  made  long  ago  (see  article  "  Protozoa," 
Ency.  Brit,  6th  edition),  and  appears  to  me  not  improbable, 
that  by  whatever  steps  of  change  that  high  complex  of  organic 
molecules  which  we  call  protoplasm — the  physical  basis  of  life — came 
into  existence,  it  very  probably  fed  in  the  first  few  aeons  of  its 
existence  on  the  masses  of  proteid-like  material  which,  it  may  be 
supposed,  were  formed  in  no  small  quantity  as  antecedents  to  the 
final  evolution  of  living  matter.  If  this  were  the  case,  the  mode  of 
nutrition  of  the  first  living  things  must  have  been  similar  to  that 
of  animals  and  unlike  that  of  plants.  At  a  later  stage  chlorophyll 
was  evolved,  the  decomposition  of  carbonic  acid  became  possible, 
and  the  Plant  series  was  started. 

In  accordance  with  this  conception,  we  must  look  for  the 
representatives  of  the  most  primitive  forms  of  life  amongst  the 
minute  Protozoa,  possessing  the  simplest  methods  of  nourishing 
themselves  by  the  digestion  of  already  elaborated  proteid.  Such 
are  the  Mycetozoa,  which  digest  dead  organic  material  by  contact, 
creeping  in  the  form  of  naked  plasmodia  of  many  inches  in  area 
over  organic  debris ;  such,  too,  are  the  minute  single  cells  of  naked 
protoplasm  taking  in  particles  of  proteid  food  by  extemporised 
mouths  and  digesting  them  in  the  cell-body,  whilst  prehensile  and 
motor  organs  are  furnished  by  the  extension  of  the  cell-protoplasm 
in  the  form  of  lobose  processes,  radiating  filaments,  or  single  or 
double  vibratile  flagella.  The  earliest  plants,  the  Protophyta, 
were,  it  seems  most  probable,  derived  from  flagellate  colony- 
building  Protozoa  (similar  to  the  Volvocinese),  which  had,  at  first 
without  discarding  their  animal-mode  of  nutrition  (Zootrophic), 
acquired  the  faculty  of  manufacturing  chlorophyll  and  supplementing 
their  ingested  nutriment  by  the  decomposition  of  carbonic  acid  and 
the  fixation  of  nitrogen  (Mixotrophic).  The  step  from  this  to  a 
purely  chlorophyll-given  nutrition  (Phytotrophic)  was  not  a  long 
one,  and  indeed  occurs  in  the  life-history  of  some  of  the  Flagellata 
at  the  present  day.  With  the  establishment  of  pure  Phytotrophic 
nutrition  ensued  the  formation — by  simple  cell-division  and  element- 
ary variation  of  cell-aggregation — of  filamentous  green  plants  consist- 
ing of  chains  of  cells  in  single  series ;  to  these  followed  networks  of 


such  chains,  then  growth  and  division  of  the  still-connected  cells 
in  two  and  finally  in  three  dimensions,  producing  first  sheet-like 
and  finally  more  solid  structures,  the  constituent  cells  of  which 
became  variously  differentiated  and  specialised. 

Those  extremely  minute,  thread-like  (Leptothrix,  Spirillum),  or 
rod-like  (Bacillus)  plants  devoid  of  chlorophyll,  which  often  break 
up  without  losing  vitality  into  spherules  or  into  granules  of 
even  ultramicroscopic  tenuity,  known  as  the  Schizomycetes  (or 
colloquially  Bacteria),  cannot  be  considered  as  primitive.  Like  the 
Fungi  and  many  of  the  most  highly  organised  plants,  they  have 
descended  from  chlorophyll-bearing  forms,  and  have  become  adapted 
to  a  parasitic  or  saprophytic  mode  of  nutrition  whilst  retaining 
the  general  characteristics  of  growth  and  form  of  their  ancestors. 
The  intimate  connection  of  the  Schizomycetes  with  the  Oscillatoriae 
does  not  seem  to  admit  of  any  doubt,  and  forms  closely  allied  to  them 
develop  chlorophyll  as  well  as  peculiar  blue  and  red  pigmentary 
substances,  the  function  of  which  is  obscure  but  may  be  related 
to  their  modified  nutritional  processes.  We  are  thus  led  to  regard 
all  the  non-filamentous,  non-chlorophylligerous  microscopic  forms 
which  are  not  referable  to  the  Schizomycetes  or  to  the  simpler 
Fungi  as  "Protozoa."  The  debatable  ground  is  limited  to  the 
chlorophyll-forming  Flagellata,  amongst  which  are  some  which, 
being  devoid  of  mouth  and  at  all  periods  of  their  growth  incapable 
of  zootrophic  activity,  are  yet  so  closely  allied  in  life-history  and 
structure  with  truly  zootrophic  species  that  it  is  not  possible  to 
draw  a  sharp  line  and  assign  them  definitely  either  to  the  Animal 
or  to  the  Plant  series.  Such  are  the  Volvocineans,  which  zoologists 
will  probably  for  some  time  to  come  consider  it  desirable  (as  we  do 
in  the  present  treatise)  to  treat  of  in  the  description  of  the  Animal 
series,  whilst  botanists  will  find  it  equally  desirable  to  discuss 
them  in  connection  with  closely  allied  minute  Plants. 

In  view  of  these  considerations,  we  consider  the  following 
groups  of  the  simplest  organisms  as  belonging  to  the  Animal 
series,  and  as  constituting  a  lowest  "  grade "  of  animal  organisa- 
tion, to  which  the  term  Protozoa  is  applicable.  The  groups  in 
question  are  given  the  title  of  "classes,"  but  it  will  readily  be 
understood  that  it  is  not  intended  to  imply  by  that  term  that 
they  have  any  exact  equivalence  in  the  amount  of  divergence 
from  one  another  to  that  which  is  presented  by  the  "  classes  "  of 
any  one  of  the  phyla  of  the  Metazoa. 

PROTOZOA. — Class  1,  Proteomyxa;  Class  2,  Heliozoa;  Class  3, 

Mycetozoa  ;  Class  4,  Lobosa ;  Class  5,  Radiolaria  ;  Class  6, 

Mastigophora ;  Class  7,  Sporozoa;  Class  8,  Ciliata;  Class  9, 



Formerly  the  name  Protozoa  was  used  for  a  sub-kingdom  of  the 
Animal  Kingdom  equivalent  in  value  to  other  sub-kingdoms  which 
were  enumerated  as  the  Coelentera,  the  Vermes,  the  Arthropoda,  the 
Echinoderma,  the  Mollusca,  and  the  Vertebrata.  In  its  earlier  use 
the  great  division  "  Protozoa "  was  made  to  include  the  Sponges, 
which  we  now  assign  to  a  divergent  line  of  descent,  the  Parazoa, 
opposed  to  the  main  line,  the  Enterozoa,  in  the  higher  grade  of 
animals  called  the  Metazoa.  The  removal  of  the  Sponges  from 
association  with  the  Protozoa  is  chiefly  due  to  the  initiative  of 
Ernst  Haeckel.  By  this  step  it  became  possible  to  give  something 
like  a  definite  characterisation  of  the  Protozoa  and  to  mark  them 
off  from  all  the  higher  animals.  They  are  definitely  characterised 
by  the  fact  expressed  in  the  English  name  Cell-animals  (Plasti- 
dozoa),  or  less  correctly  unicellular  animals,  whilst  all  the  higher 
animals  or  Metazoa  (inclusive  of  the  Sponges)  are  Tissue-animals 
(Histozoa).  The  fact  indicated  in  these  terms  is  that  in 
Protozoa  a  single  cell  or  a  colony  of  equi-pollent  cells  is  the 
organic  "individual,"  whilst  in  the  Metazoa  the  "individual" 
is  built  up  by  cells  which  are  differentiated  into  at  least  two 
layers  or  tissues,  the  cells  of  each  tissue  being  of  like  value 
and  origin  with  its  fellow -cells  of  that  tissue,  but  differing 
essentially  in  structure,  function,  and  origin  from  the  cells  of  the 
other  tissue  or  tissues.  These  statements  will  be  found  on  critical 
examination  to  hold  good  in  view  of  our  present  knowledge  of  both 
Protozoa  and  Metazoa.  Most  of  the  Protozoa  are  unicellular,  and 
in  those  which  form  many-celled  colonies,  such  as  the  Mycetozoa, 
some  of  the  Iladiolaria,  Mastigophora,  Ciliata,  and  Acinetaria,  there 
is  no  tendency  for  those  cells  to  differentiate  into  groups  of  cells  of 
like  structure  and  function  to  one  another,  but  differing  in  structure 
and  function  from  another  group  or  groups  present  in  the  same 
colony.  The  only  approach  to  an  exception  to  this  generalisation 
is  found  in  the  specialisation  of  a  cell  here  and  there  in  the  colony 
as  a  reproductive  cell;  but,  on  the  other  hand,  it  is  to  be  noted  that  any 
cell  in  the  •  colony  is  potentially  a  reproductive  cell,  and  there  is  no 
differentiation  of  a  congeries  or  tissue  of  cells  for  reproductive  pur- 
poses in  the  general  plan  of  the  colonial  structure.1  It  appears  to 
be  the  fact  that  we  do  not  know  of  any  forms  at  present  existing 
which  furnish  a  transition  from  Protozoa  to  the  Metazoa.  There 

1  Though  the  existence  of  at  least  two  "tissues"  in  the  Metazoa  suffices  to  dis- 
tinguish them  from  all  Protozoa,  it  may  legitimately  be  contended  that  the  congeries 
of  cells  forming  the  colony  of  certain  Protozoa  (e.g.  Volvox)  is  rather  of  the  nature  of 
a  "tissue"  than  of  a  merely  loosely  adherent  association  of  cells  which,  as  we  see 
in  many  Protozoan  colonies,  can  and  do  separate  freely  and  irregularly  from  such 


have  been  descriptions  of  supposed  independent  organisms  sug- 
gesting such  intermediate  character  (Trichoplax  and  others),  but 
the  true  nature  and  history  of  these  structures  have  not  been  placed 
on  a  definite  basis,  and  do  not  really  admit  of  discussion.  The 
nearest  case  of  a  transitional  form  appears  to  be  the  Choano- 
flagellate  "  Proterospongia "  of  Savile  Kent,  which  has  been 
observed  on  several  different  occasions  from  different  localities. 
It  combines  in  one  colony  "  amoebocytes  "  and  "  choanocytes,"  but 
it  appears  that  the  one  form  of  cell  develops  into  the  other.  It  is 
certainly  not  unreasonable  to  regard  Proterospongia  as  a  step 
forward  from  the  Choanoflagellata  in  the  direction  of  the  Parazoa. 
There  is  no  instance  of  equally  definite  character  tending  to 
connect  Protozoa  of  any  class  with  the  Enterozoa. 

Until  recently  it  was  possible  to  add  to  this  distinction  between 
Protozoa  and  Metazoa  the  very  striking  one  that  all  Metazoa 
reproduce  by  means  of  fertilised  egg-cells  (as  well  as  by  other 
processes),  such  fertilised  cells  being  the  result  of  the  union  of 
specially  developed  egg-cells  and  sperm-cells.  Conjugation  of  two 
cells  similar  to  one  another  as  a  preparation  to  multiplication  by 
fission  was  known  and  described  in  several  Protozoa,  but  the  special 
units,  the  static  female  egg-cell  and  the  motile  male  "  spermatozoid," 
were  unknown  in  Protozoa.  The  apparent  exception  to  this  pre- 
sented by  some  of  the  Volvocinean  Flagellata  was  regarded  as  a 
reason  for  assigning  these  organisms  to  the  pedigree  or  great  series 
of  Plants,  thus  removing  them  from  association  with  the  other 
Flagellata.  In  the  Plant  series,  though  many  groups  both  among 
the  highest  and  lowest  do  not  present  sexual  reproductive  elements 
under  the  typical  forms  of  egg-cell  and  spermatozoid  (antherozoid), 
yet  some  of  the  lowest  and  simplest,  as  well  as  some  of  the  higher, 
plants  do  develop  motile  conjugating  "  male  "  cells,  which  seem  to 
render  the  relegation  of  Volwx  to  the  vegetable  series  a  reasonable 
proceeding.  Within  the  last  decade,  however,  we  have  not  only 
become  acquainted  among  undoubted  Protozoa  with  instances 
of  the  development  of  "  microgametes  "  or  small  conjugating  cells, 
Avhich  are  distinguished  by  their  size  from  the  larger  egg-cells 
or  "  macrogametes "  with  Avhich  they  fuse  in  order  to  form  a 
fertilised  "germ,"  but  we  now  know  undoubted  Protozoa  which 
exhibit  the  breaking  up  of  a  parent  male  unicellular  individual  into 
a  number  of  motile  microgametes.  These  have  the  appearance  and 
characteristics  of  the  spermatozoa  of  higher  animals,  are  developed 
from  the  parent  male  cell  by  the  same  steps  as  are  spermatozoa 
from  sperm-mother-cells,  and  proceed  to  fertilise  the  female  macro- 
gametes  in  the  same  manner  as  occurs  in  the  fertilisation  of  the 
egg-cell  in  Metazoa. 

The  Coccidiidae  among  the  Sporozoa  and  certain  of  the  Haemo- 
flagellata  are  the  Protozoa  in  which  this  phenomenon  has  been 


carefully  observed.  It  is  identical  in  its  essential  features  with  the 
sexual  reproductive  phenomena  of  the  colonial  Flagellate,  Volvox 
fjlobator.  Not  only  so,  but  the  egg -cells  and  spermatozoa  thus 
developed  and  uniting  are  identical  in  character  with  the  egg-cells 
and  antherozoids  of  a  vast  series  of  lower  and  higher  plants,  and 
with  those  of  the  whole  series  of  Metazoa.  A  very  important  link 
in  the  genetic  relationships  of  Plants  and  Animals  is  thus  established. 
There  is  no  occasion  to  suppose  that  they  have  independently 
developed  the  typical  form  of  the  male  and  the  female  reproductive 
particles.  The  plants  have  inherited  this  from  the  Protozoa  which 
gave  rise  to  the  earliest  chlorophylligerous,  phytotrophic  organisms. 
It  is  perhaps  necessary  to  remark  that  further  observation  is 
necessary  in  these  lowest  forms  as  to  the  precise  steps  in  the 
preparation  of  the  nucleus  and  its  chromatin  in  each  of  the 
conjugating  gametes  for  the  definite  union  of  fertilisation.  There 
is  abundant  evidence  that  it  is  of  the  same  nature  as  that  which 
occurs  in  the  sexual  cells  of  higher  organisms,  but  in  special  details 
we  may  have  to  recognise  some  differences. 


The  question  as  to  whether  the  various  classes  of  Protozoa  are 
to  be  regarded  as  nine  separately  divergent  lines  of  descent,  starting 
from  a  common  primitive  ancestry  not  represented  at  the  present 
time  by  any  one  of  them,  or  whether  some  of  them  possess  closer 
genetic  relationship  inter  se  than  do  others,  is  a  very  difficult  one. 
It  has  been  proposed  at  various  times  to  seek  for  evidence  of  such 
closer  affinity  in  the  development  of  a  cortical  firmer  layer  of  the 
cell-protoplasm  (as  in  most  Sporozoa  and  in  the  Ciliata),  as  opposed 
to  the  retention  of  the  uniform  viscid  character  of  the  protoplasm 
(Lankester,  Ency.  Brit.,  article  "Protozoa"),  and  again  it  has  been 
considered  probable  that  all  those  forms  which  produce  temporary 
lobose  or  filnmentar  extensions  of  the  protoplasm,  as  locomotor  or 
grasping  organs,  may  have  a  genetic  community  of  origin  which 
separates  them  from  those  provided  with  either  isolated  flagella  or 
with  "  cilia  "  of  vibratile  protoplasm.  Some  or  other,  however,  of 
the  forms  which  it  is  found  necessary,  on  account  of  the  affinities 
indicated  by  their  life-histories  and  other  details  of  structure,  to 
class  as  Flagellata  (Mastigophora)  exhibit  combinations  of  characters 
which  render  both  these  attempts  at  grouping  unsatisfactory. 

We  find  Flagellata  (see  the  section  on  this  group)  which  produce 
extensive  amoeboid  processes,  and  yet  possess  a  flagellum,  whilst 
the  majority  have  a  distinctly  corticate  protoplasm.  Among  the 
Sporozoa  (for  which  refer  to  the  section  on  that  group  in  the  second 
fascicle  of  Part  I.  of  this  treatise),  which  are  with  these  rare  excep- 
tions strongly  corticate,  we  find  genera  which  produce  lobe-like  and 


pointed  "pseudopodia"  from  their  superficial  protoplasm  (Zygoco- 
metes  and  others).  It  seems  that  in  any  attempt  at  a  phylogeny  of 
the  Protozoa  we  should  have  to  treat  the  assemblage  of  forms  now 
classed  as  Mastigophora  (Flagellata)  as  a  central  group  from  which 
the  other  eight  classes  have  been  derived,  whilst  embracing  in 
itself  several  specialised  lines  of  descent,  including  that  which  has 
given  rise  to  the  primitive  green  plants. 

The  indication  of  a  higher  and  later  elaboration  of  structure, 
as  distinct  from  a  lower  and  more  primitive,  by  means  of  the 
classifieatory  artifice  of  "  grades,"  has,  however,  been  introduced  in 
the  present  work  by  Professor  Hickson  in  regard  to  the  classes  of 
Protozoa  by  a  consideration  of  the  cell -nucleus.  The  condition 
of  this  important  structure  justifies,  he  considers,  the  separation  of 
the  classes  of  Protozoa  into  a  lower  and  a  higher  grade — the 
Homokaryota  and  the  Heterokaryota — and  it  is  not  improbable 
that  further  study  of  the  lower  grade  will  lead  to  the  subdivision 
of  that  assemblage  into  sub-grades. 

The  history  of  the  nucleus  of  the  corpuscle  of  protoplasm,  that 
corpuscle  which  it  is  customary  to  regard  under  the  name  of  "  the 
cell  "  as  the  unit  of  living  structure,  is  at  present  absolutely  un- 
known and  altogether  a  matter  of  conjecture.  It  may  perhaps  be 
conceded  as  highly  probable  that  the  earliest  protoplasm  was  with- 
out nucleus  or  differentiated  nuclear  material.  It  is  a  legitimate 
contention  that  such  a  substance  should  not  be  called  "  protoplasm  " 
at  all,  since  Hugo  von  Mohl- invented  this  term  to  describe  the 
viscid  contents  of  a  vegetable  cell  expressly  including  the  nucleus 
a?  part  of  it.  It  was  proposed  some  twenty-five  years  ago  by 
Ed.  van  Beneden  to  call  the  earlier  non-nucleated  stage  of  living 
matter  "plasson,"  and  it  seems  to  me  by  adopting  this  term  we 
can  preserve  the  word  "  protoplasm  "  for  its  original  use.  At  the 
same  time  it  is  important  to  avoid  using  the  word  "  protoplasm,"  as 
is  not  unfrequently  done,  to  signify  the  critical  chemical  body  which 
undoubtedly  is  present  in  living  protoplasm  and  is  the  apex  of  the 
pyramid  or  the  top  of  the  fountain,  to  which  a  variety  of  chemical 
bodies  are  leading  and  from  which  another  series  of  chemical  bodies 
are  receding  at  every  moment  of  the  chemical  activity  of  living 
protoplasm.  Protoplasm  is  not  a  chemical  body  but  a  structure, 
and  its  nuclear  particles,  as  well  as  its  definitely  formed  nucleus 
consisting  of  chromatin  and  other  constituents,  are  parts  of  it.  It 
seems  necessary  to  have  a  word  by  which  to  refer  to  the  highest 
group  of  chemical  molecules  to  which  one  set  of  chemical  processes 
in  the  cell  are  always  leading  and  from  which  another  series  are  reced- 
ing. I  proposed  some  years  ago  (Ency.  Brit.,  article  "Zoology") 
to  speak  of  this  hypothetical  body  as  "  plasmogen."  In  the  same 
way  it  is  necessary  to  avoid  the  tendency  which  exists  to  employ 
the  word  "  protoplasm "  to  describe  cell-substance  both  when  con- 


sidered  as  apart  from  the  nucleus  and  when  actually  existing  in  an 
unmanipulated  simplest  living  thing  without  any  nucleus  or  nuclear 
matter.  We  have  seen  that  "  plasson  "  is  the  name  which  has  been 
proposed  for  the  latter ;  for  the  former  the  word  "  cytoplasm "  is 
frequently  used,  whilst  "  nucleoplasm  "  is  applied  to  that  part  of  the 
cell-protoplasm  which  is  the  nucleus.  The  use  of  the  word  "  cyto- 
plasm "  in  this  sense  is  certainly  objectionable,  as  it  signifies  "  the 
cell-plasm  "  and  is  merely  a  synonym  of  "  protoplasm."  It  would 
be  better  to  term  the  extra-nuclear  substance  of  the  protoplasmic 
corpuscle  "  periplasm." 

As  a  hypothesis  we  may  assume  that  living  matter  was  at  one 
time  in  the  condition  of  "  plasson,"  though  it  has  yet  to  be  shown 
that  "  plasson "  is  in  existence  at  all  at  the  present  day.  The 
next  hypothetical  stage  is  the  development  in  distinct  granular 
form  of  the  material  which  later  became  aggregated  as  a  nucleus. 
We  may  apply  the  word  "protoplasm"  to  this  stage,  with  a 
qualifying  adjective,  "  konio-karyote  "  (powder-nucleated).  This 
condition  is  known  as  actually  existing  in  certain  phases  of  the 
ciliate  Protozoa  (Trachelocerca),  and  possibly  is  to  be  recognised 
in  some  degenerate  Protophyta  and  in  some  of  the  Proteomyxa 
(whether  degenerate  or  archaic)  amongst  Protozoa.  The  third  stage 
in  the  hypothetical  development  of  protoplasm  consists  in  the 
aggregation  of  the  scattered  nuclear  granules  to  form  one  or  more 
nuclei  of  definite  structure  and  properties.  Usually  but  one  such 
nucleus  is  formed,  but  to  cover  the  case  of  the  existence  of  two  or 
more  similarly  organised  nuclei  the  term  Homokaryote  (proposed 
by  Professor  Hickson)  may  be  used  for  this  condition.  The  nucleus 
of  the  Homokaryote  cell  is  in  leading  features  of  its  structure 
identical  with  that  of  the  tissue-cells  of  higher  organisms.  It 
consists  of  nuclear  capsule,  nuclear  hyaloplasm,  and  of  chromatin 
elements.  The  optical,  chemical,  and  physiological  analysis  of  the 
nuclei  of  Protozoa  and  Protophyta  has  not  been  extended  to  a 
sufficient  number  of  instances,  at  present,  to  render  it  possible  to 
trace  the  steps  (if  they  are  still  traceable)  by  which  the  complete 
structure  of  the  nucleus  and  its  activity  in  cell-division  were  evolved. 
It  is  not  yet  clear  whether  there  are  among  Protozoa  and  Proto- 
phyta any  surviving  simpler  phases  of  the  nucleus,  or  whether 
apparently  primitive  phases  which  are  described  are  so  interpreted 
owing  to  incomplete  observation  or,  on  the  other  hand,  owe  their 
simplicity  to  a  degeneration  from  a  more  highly  developed  condition 
of  the  nucleus.  It  is,  however,  certain  that  there  are  cases  amongst 
the  Protozoa  in  which  the  structure  and  activity  of  the  nucleus  in 
cell-division  conforms  very  closely  to  those  of  the  tissue-cells  of 
higher  animals  and  plants,  if  not  absolutely  identical  with  them. 

There  are,  however,  in  certain  Protozoa  special  modifications  of 
the  nuclear  structure  which  have  not  yet  been  shown  to  occur  in 


Metazoa,  nor  in  plants.  The  most  striking  of  these  is  the  division 
of  the  nucleus  in  Ciliata  and  Acinetaria  into  two  unequal  and 
dissimilar  portions,  the  mega-nucleus  and  the  micro-nucleus,  which 
appear  to  be  the  portions  of  the  primary  nucleus  which  preside 
over  the  somatic  (the  larger)  and  reproductive  activities  (the 
smaller)  respectively.  Professor  Hickson  has  made  use  of  this 
differentiation  of  the  nucleus  into  two  parts  in  order  to  establish 
a  higher  grade  of  the  Protozoa — the  Heterokaryota  as  distinguished 
from  the  Homokaryota. 

Amongst  those  forms,  however,  which  are  classed  by  him  as 
Homokaryota,  there  are  (as  he  recognises)  certain  forms  amongst 
the  Flagellata  which  also  exhibit  a  differentiation  and  segregation 
of  the  nucleus,  but  with  functions  for  the  separated  elements 
different  from  that  shown  in  the  Ciliata.  This  case  is  that  of  the 
formation  of  a  separate  nuclear  body,  the  kineto-nucleus,  in  con- 
nection with,  and  apparently  controlling  the  activities  of,  the  large 
and  powerful  flagellum  of  certain  flagellate  forms  (Trypanosoma, 
Noctiluca).  It  seems  that  the  word  Heterokaryote  would  strictly 
apply  to  these  forms  also,  although  the  "heterosis"  is  not  the 
same  as  that  seen  in  Ciliata.  It  would  be  premature  to  attempt  to 
introduce  a  terminology  indicating  these  different  specialisations  of 
nuclear  structure  in  the  Protozoa  until  much  further  study  has 
been  given  to  the  subject.  It  is  not  at  all  improbable  that  researches 
which  are  now  in  progress  will  in  the  course  of  a  few  years  giA^e 
us,  first  of  all,  a  better  understanding  of  the  chemical  nature  and 
activities  of  the  substances  which  are  merely  brought  into  view 
by  colour-staining  as  form-elements  in  the  nucleus,1  and  secondly, 
a  far  more  critical  knowledge  than  we  at  present  possess  of  the 
rudimentarily  aggregated  and  diffuse  stainable  matter  which  is 
interpreted  as  "  nucleus  "  in  some  of  the  Protozoa,  in  some  of  the 
Cyanophyceae,  in  Schizomycetes,  and  in  the  yeasts  and  hyphae 
of  lower  fungi. 

Whilst  therefore  recognising  the  important  separation  of  the 
Ciliata  and  Acinetaria  effected  by  having  regard  to  the  nuclear 
structure  of  those  groups  and  that  of  the  other  classes  of  Protozoa, 
so  far  as  we  at  present  know  them,  I  am  unwilling  to  emphasise  the 
arrangement  of  the  Protozoa  into  grades  according  to  their  nuclear 
structure  in  the  present  state  of  knowledge.  I  should  not  wish  to 
go  farther  at  present  in  grouping  the  classes  of  Protozoa  than  to 
suggest  that  they  should  be  considered  as  diverging  lines  of  descent 
radiating  from  a  central  group  which  possessed  the  combination  of 
characters  presented  at  the  present  day  by  the  simpler  Flagellata. 

1  The  researches  of  Professor  Macallum  of  Montreal  iii  this  direction  will,  it 
may  be  hoped,  be  continued  and  developed. 



IN  the  study  of  the  Protozoa  a  number  of  forms  are  found 
which  are  difficult  to  place  in  any  of  the  larger  orders  or  families. 
The  difficulty  arises  in  many  cases  from  what  is  called  their 
simplicity  of  structure,  and  partly  from  our  ignorance  of  their  entire 
life-history.  The  more  we  learn  of  the  structure  of  the  Protozoa, 
the  more  hazardous  does  it  become  to  apply  the  expression  "  simple  " 
to  any  living  organism,  but  what  is  really  meant  by  the  term 
"  simple  "  as  applied  to  these  organisms  is  that  they  exhibit  no 
definite  structure  or  structures  such  as  skeleton,  flagella,  or  nuclei 
that  are  so  constant  in  their  form  and  character  that  they  can  be 
seized  upon  by  the  systematist  and  used  for  purposes  of  classifica- 
tion. When  characters  of  this  description  appear  during  one  phase 
only  of  the  life-history  of  an  organism  they  may  indicate  its 
affinities  if  not  its  true  systematic  position,  but  when  the  life-history 
is  not  completely  known  there  may  be  no  characters  which  can 
possibly  serve  for  placing  the  organism  with  others  in  any 
system  of  classification.  In  the  early  history  of  Protozoology  there 
was  a  time  when  it  was  considered  that  some  of  the  very  small 
and  obscure  organisms  consisted  of  a  cytode  of  protoplasm  in 
which  there  was  no  structure  corresponding  with  the  nucleus  of  the 
higher  organisms  and  cells.  Such  organisms  were  placed  in  a  class 
Monera  by  Haeckel  in  1868.  Subsequent  researches  proved  that 
in  many  of  these  organisms  one  or  many  minute  structures  occur 
which  give  the  same  reactions  as  the  chromatin  of  the  nucleus, 
and  the  conclusion  was,  in  some  cases  too  hastily,  drawn  that  all 
of  them  would  in  time  be  shown  to  be  nucleated.  Modern 
researches  on  the  nuclear  structures  of  Protozoa  have  thrown 
much  light  on  this  vexed  question.  They  have  shown  that  the 
nucleus  may  discharge  into  the  cytoplasm,  or  give  rise  by  total 
fragmentation  to,  a  number  of  minute  granules  of  chromatin — the 
chromidia — and  that  these  granules  do  not  degenerate,  but  retaining 
their  vitality  may  again  aggregate  together  in  the  formation  of  new 
nuclei.  There  may  thus  occur  in  the  life-history  of  the  higher 
Protozoa  a  stage  which  is  strictly  speaking  non-nucleate  (akaryote). 

1  By  Prof.  S.  J.  Hickson,  F.R.S. 

1  i 


This  does  not  imply,  however,  that  the  organism  is  at  this  stage 
devoid  of  nucleoplasm,  but  that  the  nucleoplasm  is  not  concentrated 
in  the  form  of  a  definite  nucleus  or  kernel  but  is  scattered  or 
diffused.  This  conception  may  be  expressed  by  saying  that  the 
stage  is  akaryote  but  is  not  moneran.  There  is  no  nucleus  but 
there  is  nucleoplasm.  In  Amoeba,  Pelomyxa,  and  others  in  which 
such  a  stage  occurs  the  nucleus  is  present  during  the  greater 
part  of  the  life-cycle,  the  akaryote  stage  being  antecedent  only  to 
nuclear  multiplication  or  gametogenesis. 

In  the  Proteomyxa,  on  the  other  hand,  the  akaryote  condition  is, 
as  a  rule,  of  much  longer  duration,  and  it  is  possible  that  in  some 
cases  the  diffused  nucleoplasm  or  scattered  chromidia  do  not  collect 
together  in  any  stage  to  form  a  defined  nucleus. 

It  seems  probable,  then,  that  the  protoplasm  of  the  Proteomyxa 
really  represents  the  protoplasm  of  the  higher  Protozoa  and 
Metazoa  plus  the  substance  of  the  nuclei.  It  is  a  substance  which 
van  Beneden  (9)  in  1871  proposed  to  call  "the  plasson,"  that  is, 
the  formative  substance  "which  is  capable  of  becoming,  either  in 
ontogenetic  course  or  in  phylogenetic  course,  monocellular  elements 
after  that  the  chemical  elements  of  the  plasson  have  been  separated 
to  constitute  a  nucleus  and  a  protoplasmic  body." 

Our  knowledge  of  the  nucleus  or  chromidia  of  the  genera  that 
are  here  grouped  together  in  the  class  Proteomyxa  is  at  present 
very  scanty.  Vampyrellidium  is  said  to  have  a  nucleus  m  all  stages 
of  its  life- history.  Zopf  states  that  a  definite  clear  nucleus  is 
present  in  all  species  of  Fampyrella,  but  it  is  often  obscured  by 
chlorophyll  and  other  bodies  in  the  cytoplasm.  There  seems  to  be 
little  doubt,  however,  that  the  nucleus  is  not  present  in  all  stages 
of  the  vegetative  life  of  F'ampyrella,  as  several  observers  Avho 
have  carefully  re-examined  its  structure  have  failed  to  find  any 
definite  nucleus.  Recently,  however,  Dangeard  (13)  has  shown 
that  nuclei  are  present  in  the  cysts,  and  that  they  divide  by  karyo- 
kinesis.  In  Tetramyxa  there  are  said  to  be  minute  nuclei,  but  these 
are  probably  chromidia.  In  Plasmodiophora  true  nuclei  are  un- 
doubtedly present  at  the  time  of  spore-formation,  as  they  have  been 
observed  to  divide  by  karyokinesis.  It  is  probable  also  that  a 
defined  nucleus  is  present  during  the  flagellate  and  amoebula  phases 
of  most  of  the  Proteomyxa  (Fig.  8,  B,  H),  but  it  is  clear  that  for 
a  time  during  the  plasmodium  stage  the  nuclei  are  disintegrated. 
In  Endyonema  nuclei  appear  to  be  wanting  during  the  active  vege- 
tative phase  in  the  filaments  of  its  host -plant  (Lingbya),  but 
definite  nuclei  are  constituted  when  the  body  contracts  in  the 
formation  of  the  zoocyst. 

Many  of  the  genera  included  in  the  group  have  been  seen  only 
once,  and  we  are  still  in  ignorance  of  their  nuclear  condition,  but 
in  Gymnophrys,  Biomyxa,  Gloidium,  Leptophrys,  and  Protamoeba, 


which   have  been   studied  by  other  observers  than  their  original 
discoverers,  no  defined  nuclei  have  been  found. 

A  considerable  number  of  genera  are  parasitic  upon  freshwater 
algae  during  at  least  one  stage  of  their  life-history,  such  as  Vam- 
pyrellidium,  F'ampyrella,  Leptophrys,  Endyonema,  Enteromyxa,  Col- 
podella,  Pseudospora,  Gymnococcus,  Aphelidium,  Tetramyxa,  and 
Ectobiella.  Tetramyxa  causes  the  formation  of  gall-like  growths 
on  Ruppict  and  other  freshwater 
plants.  Bursulla  occurs  in  horse- 
dung.  Haplococcus  occurs  in  the 
muscles  of  the  pig,  but  is  appar- 
ently harmless.  The  only  species 
that  is  of  any  economical  import- 
ance is  Plasmodiophora  brassicae, 
Woronin,  which  attacks  turnips  FIO.  i. 

and    Causes    the    disease    known    as  Ectotnella  plaUaui.  A,  a  specimen  attack- 

,/T-T                     j  rr\         »       »JTT       i        •       >;  ing  Licmophora ;  ps,  the  pseudopodium  that 

"±  ingersand  IOCS,    Or  "Hanbunes.  is  pushed  into  the  substance  of  the  host;  v, 

A    rrmsirW-iblp    nnmbpr    nf    0-pnpra  the  vacuole  formed  by  the  host  containing 

A    C                                                 OI    genera  granules  produced  by  the  digestive  action 

are   not  parasitic   and    feed   upon   of  the  pseudopodium.    B,  tiie  biflag«iiate 

,  ,  .       zoospore  of  Ectobiella.    (Alter  de  Bruyne.) 

minute     animal     and      vegetable 

organisms.       Such   genera    are    Gymnophrys,    Biomyxa,    Protomyxa, 

Gloidium,  and  others. 

In  the  vegetative  condition  the  body  emits  pseudopodia.  These 
pseudopodia  may  be  roughly  arranged  in  three  categories. 

In  Protamoeba,  Gloidium,  Enteromyxa,  etc.,  the  pseudopodia  are 
usually  lobate  like  those  characteristic  of  the  genus  Amoeba. 

In  F'ampyrella,  Colpodella,  Monobia,  Myxastrum  the  pseudopodia 
are  radiate  in  position,  very  delicate  and  rarely  anastomosing,  like 
those  of  an  Actinophrys. 

In  Biomyxa,  Gymnophrys,  Penardia  they  are  delicate  and  anasto- 
mosing, like  the  pseudopodia  of  the  Foraminifera. 

In  Endyonema,  Haplococcus,  Aphelidium,,  and  other  endoparasites 
the  form  of  the  body  is  adapted  to  the  spaces  of  the  host  and  true 
pseudopodia  are  not  formed. 

In  Protomyxa,  Myxastrum,  Protomonas,  Bursulla,  Plasmodiophora, 
a.  number  of  amoebulae  unite  to  form  a  plasmodium,  and  it  is 
possible  that  plastogamy  also  occurs  in  F'ampyrella,  Leptophrys,  and 
some  others.  In  Monobia  a  number  of  stellate  individuals  unite  to 
form  an  open  network  (Fig.  4). 

A  contractile  vacuole  does  not  usually  occur  in  Proteomyxa, 
but  it  appears  to  be  a  constant  feature  in  Gloidium  and  Ciliophrys. 
Non-contractile  vacuoles  occur  in  many  of  the  genera. 

Although  very  little  is  known  about  the  life -history  of  the 
Proteomyxa,  it  seems  probable  that  they  all,  at  some  time,  form 
.cysts  or  spores.  In  Plasmodiophora  the  protoplasm  of  the  plasmodium 
breaks  up  into  a  large  number  of  simple  spores,  which  are  able  to 


resist  desiccation,  and  are  probably  simple  hypnocysts.1     In  other 
cases  the  cysts  are  larger,  and  the  contents  give  rise  to  three  or 
four  (Vampyrella  lateritia,  Fig.   2)  or  a  large  number   (Protomyxa, 
x,       Fig.  6,  and  Diplophysalis)  of  spores,  which  may  be 
either  naked  or  protected  by  a  membrane.     These 
cysts  are  protected  by  one  or  more  cyst-membranes, 
and  the  outer  of  these  may  be  irregular  or  spiny  or 
gelatinous  in   texture.      Occasionally  three   or  four 
small  areas   on  the  cyst-wall  are  provided  with  a 
thinner  membranous  coat,  and  the  spores  escape  by 
breaking  through  these  areas  only  (Haplococcus) ;  but 
Cystic  phase  of  usuaiiy  the  cyst-wall  breaks  down  and  liberates  the 

Vampyrella.       Ihe  J  J 

contents    of   the  spores,  or  the  spore  escapes  through  any  part  of  the 

cyst  have  divided  ,  '  -T  t  i«  ii_  i 

into  four  equal  membranes.  In  spore -formation  the  protoplasm 
three'  aref  visible!  usually  discharges  all  extraneous  matters,  and  one 
(After  Lankester  large  or  a  number  of  smaller  granules  of  these 

and  Cienkowski.)          .°  •          »    i  i?ri  i 

ejecta  are  found  between  the  wall  of  the  cyst  and 
that  of  the  spores.  There  is  no  evidence  at  present  that  any 
process  of  conjugation  occurs  between  the  liberated  zoospores, 
except  in  Ciliophrys  (Cienkowski),  and,  in  the  absence  of  any 
systematic  study  of  the  nuclear  substance  of  the  spores,  we  are  not 
in  a  position  to  state  that  the  condition  of  the  nuclei  or  nucleo- 
plasrn  of  the  spores  is  in  any  way  different  to  that  of  the  other 
phases  of  life.  There  is  therefore  no  justification  whatever  for 
the  assumption  that  any  form  of  cyst -formation  indicates  or  is 
associated  with  a  sexual  process.1 

A  remarkable  phenomenon  has  recently  been  described  by  de 
Bruyne  in  Leptophrys  mllosa.  After  a  period  of  feeding,  the  animal 
becomes  spherical  in  shape 
and  enters  upon  a  period  of 
rest.  From  the  surface  there 
are  protruded  a  number  of  deli- 
cate filaments  (Fig.  3)  which 
terminate  in  hyaline  globules. 
These  globules  are  discharged 
and  the  filaments  after  some 
time  are  slowly  withdrawn. 

When      conditions      are 
favourable      there      emerge 

from    the    Cyst    One    Or    more         Leptophrys  vlllosa.    A,  a  specimen  actively  feed- 
/»T         j.  ing,  showing,  v,  a  large  non  -  contractile  vacuole ; 

(iUOnadineae  aZOO-    d,  the  diatoms  on  which  it  is  feeding  ;  and  t,  a  tuft 


Fio.  3. 

<vr      rmo      /-»• 

<  p 

of  pointed  pseudopodia  at  the  posterior  end  of  the 
body.     B,  a  resting  stage  of  the  same  animal,  pro- 


sporeae,  j 

more  flagellulae  (Monadineae     villed  with  filamentous  processes,  p,  which  discharge 
r-r        e\          mi         minute  globules,  s.p,  of  hyaline  protoplasm.     (After 
ZOOSpOreae,     Zopf).        Ihe    deBruyne.) 

1  According  to  von  Prowazek  the  nuclei  of  the  spores   of  Plasmodiophora  are 
formed  by  karyogamy  (Arb.  aus  den  kaiserl.  Gesundheitsamte,  xxii.,  1905,  p.  396). 


amoebulae  either  grow  and  become  Actinophrys-like  in  form  (l~am- 
pyrella)  or  unite  to  form  plasmoclia  (Leptopkrys,  Endyomma,  etc.). 

The  flagellulae  are  provided  usually  with  one,  but  sometimes 
two  (Dtplophysalis,  Gymnococcus)  whip-like  cilia,  and  sometimes  also 
with  a  vacuole.  They  sometimes  swim  about  actively  and  attack 
the  organisms  on  which  they  feed  (Cdpoddla,  Fig.  8,  A);  but  usually 
they  soon  withdraw  their  cilia  and  become  amoeboid  in  shape,  and 
the  amoebulae  thus  formed  either  unite  to  form  plasmodia  or  grow 
independently  into  the  adult  form. 

The  classification  of  Proteomyxa  has  always  presented  innumer- 
able difficulties,  and  even  at  the  present  day  our  knowledge  is  so 
incomplete  that  nothing  better  than  a  tentative  arrangement  of  the 
genera  can  be  suggested. 

A  large  number  of  the  genera  were  placed  in  a  division 
(Monadineae)  of  the  Mycetozoa  (Pilzthiere)  by  Zopf,  others  are 
regarded  as  Foraminifera  nuda  by  Ilhumbler,  and  Biitschli  included 
several  of  the  genera  in  the  Heliozoa. 

Zopf  further  divided  his  genera  into  two  groups,  the  Mona- 
dineae azoosporeae  and  the  Monadineae  zoosporeae.  In  the  former 
the  cysts  give  rise  to  amoebulae,  and  in  the  latter  to  flagellulae. 
It  does  not  appear  satisfactory,  however,  to  use  the  characters 
of  the  swarm-spores  alone  as  a  basis  of  classification.  Pseudospwa, 
with  a  flagellate  zoospore,  is  clearly  related  to  Vampyrella  and 
its  allies,  which  have  an  amoebulate  zoospore ;  and  Enteromyxa,, 
Myxastrum,  and  other  genera,  with  an  amoebulate  zoospore,  appear 
to  have  no  close  relation  to  Vampyrella. 

FIG.  4. 

Monobia  confluens.    A  number  of  individuals  connected  together  by  protoplasmic  strands 
to  form  a  loose  meshwork  colony.    (After  Schneider.) 

In  attempting  to  classify  the  Proteomyxa,  certain  genera  stand 
out  as  clearly  related  to  other  groups  of  Protozoa.  Thus  Monobia 
is  closely  related  to  the  Heliozoa,  Protogenes  to  the  Foraminifera, 
Protamoeba  and  Gloidium  to  the  Gymnamoebida,  and  Plasmodiophora 


to  the  Mycetozoa.  Taking  into  consideration  the  form  assumed  by 
the  pseudopodia,  the  habit  of  plasmodium- formation,  as  well  as 
the  character  of  the  zoospores,  most  of  the  other  genera  can  be 
arranged  around  these  as  central  types.  But  there  still  remain 
some  forms  whose  affinities  are  at  present  quite  obscure,  and  these 
must  be  separated  for  the  present  into  a  group  by  themselves. 

The  genera  are  here  arranged  in  five  groups  according  to  their 
supposed  affinities  with  the  other  orders  of  Protozoa. 


The  following  two  genera  appear  to  have  affinities  with  the  Gymna- 

Nothing  whatever  is  known  concerning  their  life-history,  and  it  is 
probable  they  will  prove  to  be  but  a  stage  in  the  life-history  of  an  Amoeba. 

Protamoeba,  Haeckel,  is  like  an  Amoeba,  but  without  any  definite 
nucleus  or  contractile  vacuole.  Freshwater  and  marine.  1 10  /x  (Penard). 

Gloidium,  Sorokin  (Fig.  5),  differs  from  Protamoeba  in  possessing  a 
contractile  vacuole.  Occasionally  the  surface  is  denticulated.  Fresh- 
water, 71  fj..  G.  inquinatum,  Penard,  385  p.  The  genus  Gringa,  Frenzel, 
is  probably  a  species  of  Gloidium. 

FIG.  5. 

Four  stages  in  the  division  of  Gloidium  qitadrifidum.    c.v,  contractile  vacuoles.    (After 


The  genus  Monobia  in  this  group  is  closely  related  to  Heliozoa. 
Monopodium  and  Vampyrella  are  closely  related  to  one  another, 
and  agree  with  Vampyrellidium  and  Pseudospora  in  having  a  stage 
with  delicate  radiating  pseudopodia  like  an  Adinophrys.  Leptophrys 
has  affinities  with  Vampyrella,  but  differs  from  it  in  the  shape  of  the 
body,  which  is  irregular.  Myxastrum  is  in  some  respects  intermediate 
between  the  genera  included  in  this  group  and  those  in  Group  D. 

(IV.) l  Monobia,  Schneider  (Fig.  4).  A  number  of  Actinophrys-like 
individuals,  but  without  nucleus  or  contractile  vacuoles,  and  of  a  bluish 

1  As  the  genera  included  in  the  Proteomyxa  in  this  volume  have  been  shifted 
about  from  one  class  to  another  by  different  authors,  the  roman  figures  in  brackets 
have  been  introduced  to  indicate  to  the  reader  the  position  assigned  to  each  genus  by 
the  leading  writers  on  Protozoology,  when  it  differs  from  that  given  to  the  same  genus 
iu  the  text.  Thus  the  genera  marked  (I.)  were  referred  to  the  Monadineae  azoosporeae, 
(II.)  to  the  Monadineae  zoosporeae  of  the  Mycetozoa  by  Zopf ;  (III.)  to  the  Foraminifera 
nuda  by  Rhumbler  (22) ;  (IV.)  to  the  Heliozoa  by  Biitschli  and  Schaudinn. 


colour  by  transmitted  light,  are  united  into  a  colony  by  the  fusion  of  the 
ends  of  their  contiguous  pseudopodia.  Reproduction  by  fission  has  been 
observed,  but  no  process  of  spore-formation  is  known.  Freshwater. 

(I.),  (IV.)  Vampyrella,  Cienkowski  (Fig.  6,  5).  Several  species  of 
this  widely  distributed  genus  are  known.  There  is  an  Actinophrys  stage 
in  which,  according  to  some  authors,  there  is  a  nucleus.  Vampyrella 
lateritia  attacks  Spirogyra  by  pushing  a  lobate  pseudopodium  into  the 
cell  and  gradually  absorbing  its  contents.  V.  gomphonematis  attacks  the 
stalked  diatom  Gomphonema,  completely  surrounding  the  frustules  and 
absorbing  their  contents.  Cysts  are  formed  surrounded  by  a  single 
smooth  membrane,  the  animal  discharges  particles  of  undigested  food 

FIG.  6. 

1,  Protomyxa  aurantiaca,  Haeckel,  plasmodium  phase.  The  naked  protoplasm  shows  branched, 
reticulate  processes  and  numerous  non-contractile  filaments  It  is  in  the  act  of  engulfing  a 
Ceratium.  Shells  of  engulfed  Ciliata  (Tintinnabula)  are  embedded  deeply  in  the  endoplasm, 
a.  2,  cystic  phase  ot  Pfotomyaea;  <i,  transparent  cyst-wall;  6,  protoplasm  broken  up  into 
spores.  3,  flagellula  phase  of  Protomyxa.  4,  amoebula  phase  of  the  same,  the  form  assumed  after 
a  short  period  by  the  flajjellulae.  5,  Vampyrella  lateritia.  Cienk.  Actinophrys  stage  penetrating 
a  cell  of  Spirogyra,  b,  by  a  process  of  its  protoplasm,  c,  and  taking  up  the  substance  of  the  Spiro- 
gyra cell,  some  of  which  is  seen  within  the  Vampyrella,  a.  6,  large  individuals  of  Vampyrella 
.showing  pseudopodia,  e,  and  food-particles,  a.  (From  Lankester,  after  Haeckel  and  Cienkowski.) 

materials  and  these  are  found  with  the  shrunken  protoplasm  within  the 
cyst- wall.  Occasionally  a  second  membrane  is  formed  around  the 
shrunken  protoplasm.  The  protoplasm  divides  within  the  cyst-wall,  and 
the  nuclei  of  the  spores  thus  formed  are  2  p.  in  diameter  and  divide 
by  karyokinesis.  From  the  cyst  there  escape  one,  but  usually  four 
or  five  amoebulae,  which  soon  develop  radiate  pseudopodia  and  float 
away  in  search  of  their  food.  In  some  species  (e.g.  V.  gomphonematis)  it 


seems  certain  that  several  individuals  may  fuse  to  form  a  plasmodium. 
No  contractile  vacuoles  occur  at  any  stage.  The  size  varies  consider- 
ably, 20-70  p..  They  are  nearly  all  freshwater  forms,  but  one  species, 
V.  gomphonematis,  is  also  marine. 

Monadopsis,  Klein,  is  probably  a  species  of  Vampyrella. 

(I.)  Vampyrellidium,  Zopf.  This  genus  is  parasitic  on  freshwater 
Algae,  particularly  on  Lingbya.  Two  kinds  of  cysts  are  formed,  the 
zoocysts  with  a  clear  homogeneous  membrane,  and  the  hypnocysts  with  a 
thicker  membrane.  In  other  respects  it  is  closely  related  to  Vampyrella.  A 
nucleus  surrounded  by  a  hyaline  area  is  said  (Zopf)  to  occur  at  every  stage. 

(I.)  Leptophrys,  Hertwig  and  Lesser  (Fig.  3),  appears  to  be  closely 
related  to  Vampyrella,  but  it  forms  larger  vacuolated  plasmodia  by  the 
fusion  of  the  amoeboid  zoospores.  It  is  also  characterised  by  the  presence 
in  the  protoplasm  of  numerous  paramylum  granules.  Like  Vampyrella 
it  is  found  parasitic  on  various  freshwater  lower  Algae.  It  is  either 
colourless  or  tinged  with  chlorophyll.  The  cysts  are  sometimes  0'25  mm. 
in  diameter.  They  give  rise  to  three  or  four  amoeboid  zoospores.  No 
nuclei  have  been  observed  at  any  stage. 

(IV.)  Monopodium  (Haeckelina),  Mereschkowsky,  is  an  Actinophrys-like 
form  with  hyaline  protoplasm  and  very  delicate  radiating  pseudopodia 
attached  to  foreign  bodies  by  a  stalk.  0'2  mm.  White  Sea.  Arclierina 
(see  p.  33). 

(IV.)  Nuclearia,  Cienkowski  (Fig.  8,  E),  also  appears  to  be  related  to 
Vampyrella,  but  as  a  nucleus  or  nuclei  and  contractile  vacuoles  have  been 
observed  by  several  authors,  it  is  perhaps  more  natural  to  regard  it  as  a 
member  of  the  order  Heliozoa. 

(II.)  Pseudospora,1  Cienkowski, is  a  small  Proteomyxan,  3-4  //,,  which  feeds 
upon  Oedogonium,  Spirogyra,  etc.  It  is  related  to  Gymnococcus  and  other 
members  of  Group  C  in  producing  flagellate  zoospores.  These  zoospores, 
provided  with  one  or  two  flagella  and  a  minute  nucleus,  penetrate  the 
bells  of  the  host-plant  and  give  rise  to  an  Actinophrys-like  stage,  but 
they  do  not  fuse  to  form  a  plasmodium.  When  they  are  fully  fed  the 
numerous  pseudopodia  are  withdrawn  and  an  amoeboid  form  is  assumed 
previous  to  encystment  (Fig.  8,  B,  C).  Diplophysalis,  Zopf,  seems  to  be 
closely  related  to  Pseudospora. 

(I.),  (IV)  Myxastrum,  Haeckel,  was  found  on  the  shores  of  the 
Canary  Islands  and  is  marine.  It  has  a  stage  with  numerous  radiating 
pseudopodia,  but  forms  plasmodia  which  attain  to  0'5  mm.  in  diameter. 
The  plasmodium  encysts  as  a  whole  and  the  protoplasm  forms  100  or 
more  spores  which  give  rise  to  amoeboid  zoospores. 

(IV.)  GiliophrySj  Cienkowski  (Fig.  8,  G,  H),  probably  belongs  to  this 
group.  It  is  similar  to  Nuclearia  in  some  respects,  but  at  times  it  with- 
draws its  radiating  pseudopodia,  becomes  oval  in  shape,  and  swims  rapidly 
by  means  of  a  long  flagellum.  Freshwater. 

In  this   group  there  is  a  stage  when  fine   branching   and  anasto- 

_  J  For  Pseiidospora  volcods,  see  Mastigophora,  p.  168. 


niosing  pseudopodia  are  formed  and  the  affinities  seem  to  be  with  the 
Foraminifera.  Arachnula  has  some  affinities  with  Nudearia  and  is  re- 
garded as  a  Heliozoon  by  some  authors. 

(III.)    Protogenes,    Haeckel    (Fig.    7),   is    a  small    spherical    organism 
with  very  numerous  and  delicate  radiating  and  anastomosing  pseudopodia 
Neither  vacuoles  nor  nuclei  have 
been  observed.      Marine. 

(III.)  Biomyxa,  Leidy,  is  a 
widespread  genus  occurring  both 
in  fresh  and  salt  water.  It 
passes  though  a  spherical  stage 
with  radiating  pseudopodia,  but 
afterwards  assumes  a  variety  of 
.elongated  or  outstretched  shapes 
with  a  few  long,  isolated,  branch- 
ing and  anastomosing  pseudo- 
podia. One  large  or  many  small 
nuclei  are  said  to  occur  (Rhum- 
bler).  In  B.  vagans  there  are 
numerous  minute  contractile  (?) 
vacuoles,  but  in  B.  (Gymnophrys) 
cometa  there  are  none.  It  occurs 
in  swampy  sphagnum  ground  in 
this  country.  No  definite  nuclei 
have  been  observed  and  nothing 
is  known  concerning  its  life- 
history.  The  genera  Gymnophrys, 
•Cienkowski  (Fig.  8,  D),  and 

Penardia,  Cash,  seem  to  be  allied  to  Biomyxa.  It  has  been  suggested 
by  Archer  that  Gymnophrys  is  but  a  detached  portion  of  a  Gromia, 
and  West  (27)  has  found  it  in  a  collection  containing  a  large  number 
of  specimens  of  this  Foraminifer. 

(III.)  Arachnula,  Cienkowski  (Fig.  8,  F),  also  is  closely  related  to 
Biomyxa,  but  it  forms  long  strands  terminating  in  branching  extremities 
provided  with  tufts  of  delicate  anastomosing  pseudopodia.  Cysts  have 
been  described.  It  is  found  in  fresh  and  brackish  water. 

(III.)  Pontomyxa,  Topsent,  is  a  form  closely  allied  to  Biomyxa  and 
Penardia.  The  body  assumes  a  variety  of  ribboned  or  dendritic  forms, 
with  numerous  or  interrupted  groups  of  anastomosing  pseudopodia. 
P.  pallida  from  the  Mediterranean  Sea  is  colourless,  but  P.  flava,  like 
Penardia,  is  golden  yellow  in  colour.  P.  flava  was  found  in  35-50 
metres  oft"  the  French  coast  and  also  in  the  Mediterranean  Sea.  The 
nuclei  are  said  to  be  very  small  and  reproduction  occurs  by  multiple 

(III.)  Rhizoplasma,  Verworn  (26).  Spherical  or  sausage-shaped  bodies 
of  an  orange-red  colour,  with  numerous  anastomosing  pseudopodia,  5-10 
mm.  in  diameter  when  expanded,  found  in  the  Red  Sea,  are  placed  in 
this  genus.  There  are  1-3  large  transparent  vesicular  nuclei.  The 
.coloured  granules  circulate  in  the  pseudopodia. 

FIG.  7. 

Protogenes  primordialis,  Haeckel,  from  Schultze's 



(III.)  Didyomyxa,  Monticelli,  is  like  the  preceding  genus,  but  with 
colourless  pseudopodia.  On  Chaetomorplia  crassa  at  Naples. 

Boderia,  Wright  (Fig.  9),  is  marine,  orange  or  brown  in  colour,  with 
a  membranous  investment  (?),  from  openings  in  which  protrude  three  to 
four  long  branching  pseudopodia.  The  nucleus  or  nuclei  after  a  time 

disappear,  and  the  protoplasm  spreads  out  in  ragged  masses  on  the  slides. 
A  number  of  naviculoid  bodies  are  formed,  from  each  of  which  a  small 
amoebula  emerges  in  a  few  days.  Marine.  1-4  mm. 


Most  of  the  genera  included  in  this  group  form  plasmodia,  and  their 
affinities  seem  to  be  with  the  Mycetozoa.  No  plasmodium-formation  has 
been  found  in  Aphelidium,  Colpodella,  Pseudosporidium,  and  Pseudamphi- 


monas.  Zoospores  with  one  or  two  flagella  have  been  seen  in  all  the 
genera  except  Myxodictyiim,  Bursulla,  and  Tetramyxa.  It  is  possible  that 
Colpodella  is  related  to  the  Mastigophora. 

(III.)  Protomyxa  (Fig.  6,  1)  was  found  by  Haeckel  attached  to  the  shells 
of  Spirilla  on  the  coast  of  the  Canary  Islands,  in  the  form  of  orange-yellow 
flakes  consisting  of  branching  and  reticular  protoplasm  nourishing  itself 
by  the   ingestion   of  Diatoms  and 
Peridiniae.     This  is  a  plasmodium 
formed    by   the  union   of  several 
amoebulae.      The  plasmodium  en- 
cysts and  gives   rise   to  numerous 
flagellulae  or  swarm-spores.      The 
diameter  of  the  cyst  is  '12-'2  mm. 
The  flagellulae  pass  into  an  amoe- 
bula    phase,    and    the    amoebulae 
unite  to  form  the  plasmodium. 

Myxodictyum,  Haeckel,  consists 
of  a  number  of  protomyxa-like 
individuals  united  by  their  pseudo- 
podia  to  form  colonies.  It  is 
pelagic  in  habit  and  was  found  by 
Haeckel  at  Algeciras  in  Spain. 

(II.)  Gyinnococcus,  Zopf,  occurs 
in  Cladophora,  Diatoms,  and 
spermum.  It  forms  a  plasmodium. 
When  fully  fed  it  gives  rise  to  zoo- 
cysts,  from  which  three  to  twelve 
biflagellate  zoospores  escape. 

(II.)  Aphelidium,  Zopf,  lives  in 

the  cells  of  Colenchaeta  and  in  macerations  of  plant  tissues.  Hypnocysts 
furnished  with  an  operculum  are  formed.  A  nucleated  zoospore  with 
one  flagellum  has  been  found  in  A.  lacerans  (de  Bruyne). 

(II.)  Protomonas,  Cienkowski,  has  biflagellate  zoospores  which  become 
amoeboid  and  unite  to  form  a  plasmodium.  Freshwater  and  marine. 

(II.)  Colpodella,  Cienkowski  (Fig.  8,  A),  is  possibly  allied  to  Protomonas. 
The  zoospores  have  only  one  flagellum,  and  attack  Mastigophora  before 
they  become  amoeboid.  They  do  not,  however,  form  plasmodia. 

(II.)  Tetramyxa,  Gobel,  forms  large  galls  on  various  water-plants, 
especially  Buppia. 

(II.)  Plasmodiophora,  Woronin,  is  the  cause  of  the  disease  of  turnips 
known  as  "  Fingers  and  Toes,"  or  "  Hanburies  "  (German,  Herniekrank- 
heit).  The  spores  are  found  in  damp  ground.  Each  spore  gives  rise  to 
a  minute  nucleated  amoeboid  zoospore  with  a  single  flagellum.  This 
penetrates  into  the  cells  of  the  root  and  loses  its  flagellum.  It  increases 
in  size  and  the  nuclei  divide.  After  a  time  plasmodium-formation  begins 
by  the  fusion  of  neighbouring  amoebulae,  and  the  tissues  of  the  host-plant 
disintegrate.  As  soon  as  the  plasmodium  is  formed  the  nuclei  increase 
rapidly  by  karyokinesis,  but  according  to  Nawaschin  (21)  there  is  a  period 

Botleria  turneri. 

(After  Wright.) 


when  the  plasmodia  exhibit  no  trace  of  nuclei,  the  nuclear  substance  being 
apparently  distributed  throughout  the  whole  plasmodium.  Subsequently 
the  plasmodium  breaks  up  into  a  great  number  of  minute  spherical 

Pseudamphimonas,  de  Bruyne,  was  found  on  Caulerpa  at  Naples.  The 
zoospores  are  biflagellate  and  extremely  amoeboid.  They  withdraw  their 
flagellae,  and  two  or  three  have  been  seen  to  fuse  together  to  form  a 

(I.)  Bursulla,  Sorokin,  is  found  in  horse-dung.  A  number  of  amoebulae 
with  long  pointed  pseudopodia  unite  to  form  a  plasmodium.  The 
plasmodia  contract  and  form  either  stalked  cysts  (51  /*,),  the  contents  of 
which  divide  and  emerge  as  eight  amoebulae,  or  they  give  rise  to  naked 
spherical  cysts  with  rosy  contents  and  an  outer  cortex,  from  each  of 
which  a  single  stalked  zoospore  emerges. 


The  affinities  of  the  genera  included  in  this  group  are  quite 

(I.)  Enteromyxa,  Cienkowski,  forms,  by  the  fusion  of  amoeboid  zoospores, 
long  vermiform  plasmodia  (O'5-l  mm.)  with  short  tubercular  pseudopodia. 
These  break  up  into  segments,  which  encyst  and  give  rise  to  two  or 
seldom  more  amoeboid  zoospores.  It  feeds  on  Oscillatoria. 

(I.)  Endyonema,  Zopf,  forms  cylindrical  cysts  of  considerable  length  in 
the  threads  of  filamentous  algae.  Nuclei  are  said  to  occur  previous  to 

Ectobiella,  de  Bruyne  (Fig.  1),  was  found  in  the  form  of  a  biflagel- 
late pyriform  zoospore.  It  attacks  Licmophora  and  other  diatoms,  with- 
draws the  flagella  and  pushes  a  pseudopodium  into  the  protoplasm  of  its 
prey.  When  the  contents  of  the  diatom  are  assimilated,  the  amoeboid 
organisms  wander  away  and  encyst. 

Haplococcus,  Zopf,  is  found  in  the  muscles  of  the  pig.  Two  kinds  of 
cysts  are  described  by  Zopf,  the  zoocysts  (1 6-22 /x)  and  the  hypnocysts 
(25-30  /A).  The  membrane  surrounding  the  former  is  thinner  in  some 
places  than  elsewhere,  and  from  them  escape  six  to  fifteen  amoeboid 
spores.  The  further  history  of  the  hypnocysts  has  not  been  followed. 

Pseudosporidium,  Zopf,  was  found  by  Brass  in  vegetable  infusions. 
It  is  amoeboid  in  form,  with  short  blunt  pseudopodia,  a  nucleus,  and  a 
vacuole.  The  cysts  give  rise  to  numerous  small  flagellate  zoospores. 

Schizogenes,  Pouchet,  was  found  in  the  haemocoel  of  freshwater  Ostra- 
cods  and  Copepods.  It  consists  of  small  plastids  of  hyaline  protoplasm, 
•01-'03  mm.  without  vacuoles  or  nucleus,  of  indefinite  form,  and  devoid 
of  pseudopodia.  It  divides  into  parts,  which  become  new  individuals. 

BathybiuSj  Huxley,  and  Protobathybius,  Bessels,  are  no  longer  regarded 
as  living  organisms.  It  seems  probable  that  both  forms  represent  a  colloid 
precipitate  of  calcium  sulphate  thrown  down  by  the  action  of  alcohol  on 
sea-water  (Murray). 

1  See  Note,  p.  4. 



The  following  recent  general  works  on  Protozoology  will  be  found  useful  to 
students  : — 

1.  Braun.     Animal  Parasites  of  Man.     Translated  by  F.  V.  Theobald.     1906. 

2.  Biitschli,  0.     Protozoa.     Bronu's  Klassen  und  Ordnungen  des  Thierreichs. 

3.  Calkins,  G.  N.     Protozoa.     Columbia  University  Biol.  Series.     1901. 

4.  Cash,  J.     The  British  Freshwater  Rhizopoda  and  Heliozoa,  vol.  i.     Ray 

Society,  1905. 

5.  Doflcin,  F.    Die  Protozoen  als  Parasiten  und  Kraukheitserreger.    Jena,  1901. 

6.  Hartog,  M.  M.     Protozoa.     Cambridge  Natural  History,  vol.  i.,  1906. 

7.  Lamj,  A.     Lehrbuch  der  vergleichende  Anatomic.     Protozoa.     1901. 

8.  Penard,  E.     Faune  rhizopodique  du  bassin  du  Leman.     1902. 

The  following  refer  particularly  to  Proteomyxa  : — 

9.  Benedcn,  E.  van.     Q.  J.  Micr.  Sci.  xi.,  1871,  p.  254. 

10.  Brass.     Biol.  Studien,  i.,  1883-4,  p.  70.     (Pseudosporidium.) 

11.  de  Bruyne,  C.     Arch.  Biol.  x.,  1890.     (Ectobiella,  etc.) 

12.  Cienkowski.     Arch.  mikr.  Anat.,  1865,  1876. 

13.  Dangeard,  P.  A.     Le  Botaniste,  (2),  1890,  p.  33,  and  (7),  1900,  p.  131. 

14.  Gobel.     Flora,  No.  '28,  1884.     (Tetramyxa.) 

15.  Haeckel,  E.     Monogr.  der  Moneren.     Jen.  Zeits.  iv.,  1868. 

16. System.  Phylog.  der  Protist.  u.  Pflanzen.     Berlin,  1894. 

17.  Ho'<genraad,  II.  K.     Arch.  Protist.  viii.,  1907.     (Vampyrella.) 

18.  Mereschkowsky.     Arch.  mikr.  Anat.  xvi.,  1879.     (Monopodium.) 

19.  Monticelli.     Boll.  Soc.  Napoli,  xi.,  1897.     (Dictyomyxa.) 

20.  Murray,  J.     P.  R.  Soc.  London,  xxiv.,  1876. 

21.  Nawaschin.     Flora,  1899,  p.  404.     (Plasmodiophora.) 

22.  Rhumbler,  L.     Arch.  Protist.  iii.,  1904. 

23.  Schneider,  A.     Arch.  mikr.  Anat.  vii.,  1878.     (Monobia.) 

24.  Sorokin.     Ann.    Sci.    Nat.    Bot.    (6)  iii.,   1876;    Morph.   Jahrb.    iv.,   1878, 

( Gloidium. ) 

25.  Topsent,  E.     Arch.  Zool.  Exper.  (3)  i.,  1893.     (Pontomyxa.} 

26.  Verworn.     Arch.  ges.  Physiol.  Ixii.,  1896.     (Rhizoplasma.) 

27.  West,  G.  S.     J.  Linn.  Soc.  Zool.,  1901,  xxviii.  p.  308. 

28.  -      -     I.e.,  1903,  xxix.  p.  108. 

29.  Woronin.     Pringsheim's  Jahrbiicher,  xi.     (Plasmodiophora.) 

30.  Wright,  S.     Journ.  Anat.  Physiol.  i.,  1867.     (Boderia.) 

31.  Zojif,  W.     Handbuch  der  Botanik.     Edited  by  A.  Schenk.     Bd.  iii.,  pt.  2r 


THE   PEOTOZOA   (continued) 


THE  term  Heliozoa  is  commonly  used  to  include  a  number  of 
Protozoa,  generally  inhabitants  of  fresh  water,  with  few  characters 
in  common  except  the  possession  of  straight,  radial  pseudopodia 
which  rarely  anastomose,  and  the  absence  of  anything  like  a 
capsular  membrane  dividing  a  central  portion  of  the  body  from  a 

peripheral  portion,  such  as  is  found 
among  the  Eadiolaria.  The  more 
highly  specialised  members  of  the 
group  have  a  spheroidal  body,  which 
rarely  exhibits  amoeboid  change  of 
shape,  divided  into  a  more  vacuolated 

FIG.  1. 

Actinosphaerium  Eichhorni,  Ehrb.  A,  a  drawing 
of  an  individual  as  seen  in  optical  section  ;  c.^i,  a 
contractile  vacuole  previous  to  discharge  of  its 
contents  ;  c.  vz,  the  position  of  a  contractile  vacuole 
that  has  just  collapsed  ;  e.r,  food-vacuole  ;  r,  a 
rotifer  in  the  act  of  being  engulfed  in  a  food-vacuole. 
B,  a  small  portion  of  the  ectoplasm  of  the  same 
animal  very  much  enlarged  ;  N,  the  nuclei  ;  ps,  a 
pseudopodium  ;  ps.a,  the  axis  of  the  pseudopodium. 
The  axes  of  the  pseudopodia  have  been  recently 
traced  farther  into  the  ectoplasm  than  is  shown  in 
the  figure  and  into  closer  relation  with  the  nuclei. 
(After  Leidy.) 

ectoplasm  and  a  less  vacuolated  endo- 
plasm,  the  endoplasm  containing  one 
or  many  nuclei,  and  sometimes  a  per- 
manent centrosoma  distinct  from  the 
nucleus.  The  pseudopodia  are  long, 
slender,  and  stiff,  projecting  radially 
from  the  surface  of  the  body,  and 
generally  consisting  of  a  cortex  con- 
tinuous with  the  ectoplasm  and  an 

axis  prolonged  into  the  endoplasm  (Fig.  1,  ps).  In  Elaeorhanis, 
Nudearia  (Fig.  8,  E,  p.  1 0),  and  some  others  that  may  be  regarded  as 
being  on  the  border-line  between  the  Heliozoa  and  Group  B  of  the 

1  By  the  late  Prof.  W.  F.  R.  Weldon,  F.R.S.,  and  Prof.  S.  J.  Hickson,  F.R.S. 



Proteomyxa  (cf.  p.  6),  no  axial  rod  to  the  pseudopodium  has  been 
discovered.  A  skeleton  may  be  present  or  absent ;  when  present 
it  is  generally  siliceous,  though  it  may  be  in  part  chitinous  (Adino- 
lophus),  or  composed  of  a  jelly  whose  chemical  composition  is 
unknown  (Heterophrys),  or  built  up  of  foreign  particles  (Elaeorhanis), 

Hertwig  and  Lesser  (7),  in  a  memoir  which  established  the 
main  lines  of  the  modern  classification  of  the  group,  included  only 
those  higher  forms  whose  characters  have  been  indicated,  giving  a 
conception  of  the  Heliozoa  both  logical  and  in  many  ways  con- 
venient ;  but  such  a  treatment  neglects  a  singularly  perfect  series 
of  forms,  the  higher  members  of  which,  such  as  Nuclearia  (Fig.  8,  E, 
p.  10),  closely  resemble  undoubted  Heliozoa,  while  from  these  we 
may  pass  step  by  step  to  such  forms  as  Monobia  or  Vampyrella 
(Figs.  4  ;  6  (5),  pp.  4  and  7),  which  are  probably  more  nearly  allied 
to  the  Mycetozoa  than  to  the  typical  Heliozoa.  We  have  here,  in 
fact,  a  case  such  as  often  occurs  in  which  different  types  of  structure 
and  life-history  are  connected  by  a  series  of  intermediate  forms  so 
gradual  that  any  attempt  to  define  the  limits  of  either  must  fail. 
Under  these  circumstances,  the  limits  assigned  to  one  or  other  group 
in  a  descriptive  classification  depend  merely  on  convenience ;  the 
only  point  of  importance  is  to  frame  the  classification  in  such  a  way 
that  it  shall  not  disguise  the  real  continuity  of  the  forms  described. 
For  this  reason,  most  modern  writers,  while  recognising  the  great 
value  of  the  conception  formulated  by  Hertwig  and  Lesser,  have  so 
enlarged  it  as  to  include  among  the  Heliozoa  a  number  of  transi- 
tional genera  (p.  6). 

For  the  sake  of  convenience,  the  forms  that  are  included  in  the 
Heliozoa  in  this  article  are  those  in  which  one  or  more  definitely 
formed  nuclei  are  present  during  the  vegetative  phases  of  life, 
together  with  those  genera  which  seem  to  have  the  closest  zoological 
relation  to  them  although  their  nuclei  are  not  known.  The 
genera  that  are  sometimes  classified  with  the  Heliozoa,  mainly  on 
the  ground  that  they  have  stiff  radiating  pseudopodia,  but  which 
afford  some  •  reasons  for  believing  that  their  nuclei  are  dissipated 
during  the  vegetative  phases  of  life,  are  placed  with  the  Proteomyxa 
(see  p.  6). 

It  will  be  convenient  to  consider  first  the  structure  of  the  more 
highly  specialised  forms  to  which  Hertwig  and  Lesser  proposed 
that  the  name  Heliozoa  should  be  restricted,  and  to  discuss  the 
transitional  genera  afterwards. 

The  characters  of  the  more  specialised  Heliozoa  may  be  illustrated 
by  describing  Adinophrys  sol,  the  common  freshwater  species  already 
mentioned.  The  body  is  spheroidal  and  minute,  rarely  exceeding 
0'05  mm.  in  diameter ;  in  a  healthy  undisturbed  individual  numerous 
stiff  pseudopodia,  each  considerably  longer  than  the  diameter  of  the 
body,  radiate  from  the  surface.  The  body  itself  is  divided  into  a 


clearer  coarsely  vacuolated  ectoplasm,  and  a  less  transparent  spongy 
or  feebly  vacuolated  endoplasm,  containing  a  centrally  placed  nucleus 
(Fig.  2(1),  d).  The  ectoplasm  is  normally  so  crowded  with  vacuoles 
that  it  is  reduced  to  a  mere  system  of  septa,  and  to  a  thin  layer  form- 
ing the  cortex  of  the  radial  pseudopodia.  During  the  ingestion  of 
food,  however,  an  aggregation  of  ectoplasm  takes  place,  forming  a 
short,  blunt  amoeboid  projection  by  which  the  food  is  engulfed,  and 
in  which  a  digestive  food-vacuole  is  formed  (Fig.  2(1),  a).  The  ecto- 
plasm usually  contains  a  number  of  bright,  highly  refringent  granules, 
remarkably  uniform  in  diameter,  which  are  carried  from  one  region 
to  another  by  streaming  movements  of  the  protoplasm  ;  thus  they 
may  often  be  seen  streaming  to  or  from  the  apex  of  a  radial  pseudo- 
podium,  or  towards  the  apex  on  one  side  and  away  from  it  on  the 
other.  The  number  of  these  granules  is  said  to  increase  with 
increased  nutrition,  but  their  chemical  nature  is  quite  unknown. 

FIG.  2. 

1,  Actinophrys  sol,  Ehrb.,  x  800;  o,  food-particle  lying  in  a  large  food-vacuole;  6,  deep- 
lyiii^'  finely  granular  protoplasm  ;  c,  axial  filament  of  a  pseudopodium  extended  inwards  to  the 
nucleus  ;  d,  the  centrally  placed  nucleus  ;  e,  contractile  vacuole  ;  /,  superficial,  much-vacuolated 
protoplasm.  2,  Clathrulina  elegans,  Cienk.,  x  200.  3,  Heterophrysmyriopoda,  H.  and  L.,  x  660  ; 
a,  nucleus  ;  6,  clearer  protoplasm  surrounding  the  nucleus  ;  e,  the  peculiar  felted  envelope. 
4,  Rhaphidiophrys  pallida,  V.  E.  Schultze,  x  430  ;  a,  food-particle  ;  b,  a  contractile  vacuole  (?), 
the  nucleus  is  probably  represented  by  the  circular  shaded  body  lying  below  6  ;  c,  a  food-particle ; 
rf,  the  centrosome.  The  tangentially  disposed  spicules  are  seen  arranged  in  masses  at  the 
surface.  5,  Acanthocystis  turfacea,  Carter,  x  240  ;  a,  probably  the  centrosome  ;  b,  clear  pro- 
toplasm around  the  centrosome  ;  c,  more  superficial  protoplasm  with  vacuoles  and  xanthellae  ; 
d,  coarser  siliceous  spicules ;  e,  finer  forked  siliceous  spicules ;  /,  finely  granular  layer  of 
protoplasm.  The  long  pseudopodia  stretching  beyond  the  spicules  are  not  lettered.  6,  biflagellate 
"flagellula"  of  Acanthocystis  acideata;  a,  nucleus.  7,  Flagellula  of  Clathrulina  elegans;  «, 
nucleus  ;  b,  granules  of  uncertain  composition.  8,  Astrodisculus  radians,  Green0,  x  320  ;  o,  red- 
coloured  fatty  globule  ;  6,  peripheral  homogeneous  envelope.  (From  Lankester,  after  various 

The  endoplasm  is  rarely  vacuolated,  and  the  bright  refringent 
granules  are  absent  from  it. 

In  a  normal  pseudopodium  we  can  distinguish  (1)  a  cortical 
layer,  and  (2)  an  axial  filament.  The  cortical  layer  is  continuous 
with  the  general  ectoplasm  at  the  base  of  each  pseudopodium  ;  it  is 
irregular  in  thickness,  and  may  by  a  streaming  movement  become 
aggregated  into  amoeboid  droplets  of  relatively  large  size  during 
the  seizure  of  prey  (Fig.  2  (3)).  The  effect  produced  upon  infusoria, 
small  rotifers,  and  other  ciliated  organisms  by  contact  with  the 
pseudopodia  is  a  marked  paralysis,  which  has  led  many  observers, 
from  Ehrenberg  onwards,  to  assume  that  some  poisonous  substance 
is  formed  by  or  contained  in  the  cortex;  but  direct  chemical 
evidence  of  this  is  wanting.  The  axial  filament  is  a  clear  homo- 
geneous thread,  which  runs  from  the  apex  of  a  pseudopodium 
through  the  substance  of  the  body,  to  end  in  a  central  dilatation  in 
contact  with  the  nuclear  membrane.  When  a  pseudopodium  is 
withdrawn,  its  axial  filament  disappears,  and  cannot  be  demon- 
strated by  staining  reagents  ;  in  the  living  animal  it  is  more  easily 


seen  at  some  periods  than  at  others,  and  may  even  for  a  time  dis- 
appear without  retraction  of  the  pseudopodium. 

The  nucleus  is  relatively  large,  with  an  obvious,  doubly -con- 
toured membrane.  Within  the  membrane  is  a  fine  reticulum  of 
"  linin  "  threads,  on  which  are  small  particles  of  chromatin ;  there 
is  generally  also  a  single  large  extra-reticular  mass  of  chromatin, 
forming  a  karyosomatic  "nucleolus." 

The  vacuoles  are  of  three  kinds  :  non-contractile  and  contractile 
vacuoles  which  do  not  contain  food-particles,  together  with  diges- 
tive vacuoles  which  contain  food.  The  non- contractile  vacuoles 
form  a  layer  occupying  the  whole  thickness  of  the  ectoplasm ;  they 
contain  a  clear,  colourless  fluid,  in  which  refringent  granules,  like 
those  found  in  the  ectoplasm,  may  often  be  seen  floating,  the  number 
of  such  granules  in  a  single  vacuole  being  sometimes  large.  A 
non-contractile  vacuole,  which  contains  many  granules,  sometimes 
bursts,  and  the  granules  are  scattered  in  the  surrounding  water. 
There  is  generally  only  one  contractile  vacuole,  which  rhythmically 
changes,  enlarging  slowly  until  its  diameter  may  be  about  half  that 
of  the  body,  and  then  suddenly  collapsing ;  the  cycle  of  dilatation 
and  contraction  is  completed,  at  ordinary  temperatures,  in  about 
one  minute  (40-100  seconds,  Penard  [14]).  The  function  of  the 
contractile  vacuole  is  as  obscure  in  this  as  in  other  cases.  Most 
observers  believe  that  the  fluid,  collected  during  dilatation,  is 
expelled  from  the  body  during  contraction  of  the  vacuole,  so  that 
the  whole  process  is  excretory  in  nature ;  but  while  it  is  difficult  to 
watch  an  Adinophrys  without  sharing  this  opinion,  it  is  equally 
difficult  to  demonstrate  its  truth.  The  contraction  takes  place  so 
quickly  that  it  is  impossible  to  be  sure  whether  a  rupture  of  the  body- 
wall  occurs  or  not ;  and  all  attempts  to  show  that  the  collapse  of 
the  vacuole  is  accompanied  by  a  disturbance  in  the  surrounding 
water,  such  as  would  result  from  the  forcible  expulsion  of  its  con- 
tents, have  hitherto  failed. 

Food-vacuoles  are  formed  in  the  blunt  processes  of  the  ectoplasm 
already  described.  When  fully  formed  they  contain  a  clear  fluid, 
surrounding  the  ingested  food-mass,  which  doubtless  contains  some 
solvent  in  solution,  analogous  to  those  demonstrated  in  the  similar 
vacuoles  of  amoebae  and  of  ciliata.  Formed  immediately  beneath 
the  surface  of  the  body,  the  food -vacuole  remains  throughout 
its  whole  existence  in  the  ectoplasm,  where  the  processes  of  diges- 
tion and  absorption  are  completed ;  a  vacuole  with  a  large  food- 
mass  may,  however,  travel  into  the  deeper  parts  of  the  ectoplasm. 
After  digestion  is  completed  the  residue  of  the  food -mass  remains 
in  the  vacuole  for  some  time,  being  ultimately  discharged  by  the 
bursting  of  the  vacuole  at  some  part  of  the  surface  of  the  body. 

The  food  consists  of  living  organisms,  animals  and  plants. 
Smaller  prey  is  seized  by  the  blunt  ingestive  processes  alone,  with- 


out  help  from  the  radial  pseudopodia  ;  a  larger  creature  is  seized  by 
a  group  of  radial  pseudopodia,  which  converge  round  it,  generally 
(always  ?)  losing  their  axial  filaments,  and  send  out  amoeboid 
processes,  which  more  or  less  completely  engulf  the  prey.  The 
mass  formed  by  these  fused  processes  and  the  organism  they  con- 
tain travels  towards  the  body,  where  it  meets  and  fuses  with  an 
ingestive  process. 

Actinoplirys  is  capable  of  performing  various  rolling  or  creeping 
movements  on  the  bottom  of  the  pond,  but  the  creature  spends 
much  of  its  time  suspended  in  the  water,  where  it  has  a  certain 
power  of  rising  and  of  sinking,  though  the  way  in  which  this  is 
effected  is  altogether  obscure. 

At  intervals  Adinophrys  may  withdraw  its  pseudopodia,  the 
axial  filaments  of  which  disappear ;  it  may  then  secrete  a  complex 
cyst  of  two  layers — an  outer,  fairly  thick  transparent  layer  of  gela- 
tinous consistence,  within  which  is  a  second,  thinner  layer. '  After 
the  formation  of  these  layers,  the  vacuoles  disappear,  the  contractile 
vacuole  being  the  last  to  go,  and  the  whole  body  shrinks.  The 
nucleus  now  divides  mitotically  (cf.  infra,  pp.  25-27),  and  the  cyst 
divides  into  two,  each  of  which  becomes  spherical.  Within  each 
of  the  resulting  cysts  a  third  hard,  opaque  membrane  is  secreted, 
and  a  period  of  quiescence  ensues,  after  which  the  walls  are  ruptured 
and  the  creature  emerges,  new  pseudopodia  being  rapidly  formed. 
This  account  is  based  on  that  given  by  Schaudinn  (17),  who  says 
that  each  daughter- cyst  may  divide  again  before  entering  on  a 
period  of  quiescence ;  on  the  other  hand,  many  observers  describe 
a  process  of  encystment  which  is  not  accompanied  by  any  division 

Just  as  encystment  may  occur  without  fission,  so  fission  may, 
according  to  Schaudinn,  occur  without  encystment.  An  individual 
about  to  divide  in  this  way  withdraws  its  pseudopodia,  and  a 
peculiar  mitosis  takes  place,  not  accompanied  by  disappearance  of 
the  nuclear  membrane  or  by  the  formation  of  centrosomata  (infra, 
p.  28) ;  this  is  followed  by  fission  of  the  cell-body,  and  pseudo- 
podia are  shortly  afterwards  emitted. 

The  processes  of  fission  just  described,  whether  accompanied  by 
encystment  or  not,  are  asexual,  since  there  is  no  previous  fusion 
of  individuals  or  of  nuclei.  A  process  of  plastogamic  fusion,  involv- 
ing the  union  of  a  number  of  individuals  (as  a  rule  by  the  ectoplasm 
only),  without  nuclear  fusion,  frequently  occurs.  The  number 
of  individuals  so  united  is  frequently  two;  but  it  may  be  over 
thirty  (Schaudinn).  Plastogamic  individuals  lose  their  pseudo- 
podia on  the  surfaces  by  which  they  are  attached  to  each  other 
but  retain  them  elsewhere,  and  the  union  is  not  necessarily  followed 
by  a  period  of  quiescence.  Individuals  which  have  been  united  in 
Jbhis  way  for  some  time  may  separate  without  withdrawing  those 


pseudopodia  which  they  retained  during  the  plastogamy.  Schaudinn 
thinks  it  probable  that  all  recorded  cases  of  division  without  mitosis 
and  without  retraction  of  the  pseudopodia  are  really  cases  in  which 
plastogamic  individuals  have  been  seen  to  separate. 

An  observation  recently  made  by  Calkins  on  Paramecium  suggests 
a  possible  eft'ect  of  plastogamy.  The  work  of  Maupas  has  shown 
that,  after  a  certain  number  of  asexual  divisions,  Paramecium  and 
other  Ciliata,  when  grown  in  artificial  culture-media  with  a  constant 
supply  of  food  of  one  kind,  exhibit  phenomena  of  degeneration, 
which  quickly  lead  to  the  death  of  the  whole  culture,  unless 
individuals  produced  by  another  zygote  are  introduced.  If  such 
individuals  are  introduced,  plastogamy  occurs,  which  is  quickly 
followed  by  a  complicated  sexual  (karyogamic)  process ;  and  after 
this  the  "rejuvenated"  culture  can  enter  upon  another  period  of 
asexual  multiplication  (cf.  Chap.  I.  Fasc.  II.  pp.  386,  387).  Calkins 
has,  however,  shown  that  a  culture  which  exhibits  signs  of  degenera- 
tion may  be  completely  "rejuvenated"  by  purely  chemical  stimuli, 
such  as  an  appropriate  change  of  food,  and  that  if  plastogamy  alone 
be  allowed  to  occur,  the  conjugating  individuals  being  shaken  apart 
before  the  nuclear  changes  which  precede  karyogamy  have  taken 
place,  these  individuals  can  still  go  through  a  further  cycle  of 
asexual  divisions.  Nothing  analogous  to  the  phenomena  of 
"senile  degeneration"  described  by  Maupas  has  been  observed 
among  the  Heliozoa,  but  it  is  possible  that  it  may  occur,  and  that 
the  rejuvenescent  effect  of  natural  plastogamy  is  similar  to  that  of 
the  artificial  plastogamy  observed  by  Calkins. 

Although  plastogamy  is  often  followed  by  a  complete  separation 
of  individuals,  it  may  be  the  beginning  of  a  sexual  karyogamic 
process,  which  has  been  carefully  studied  by  Schaudinn.  In  this 
case  the  mass  of  individuals,  united  by  ectosarc,  sinks  to  the  bottom 
of  the  water;  the  pseudopodia  are  withdrawn,  and  a  common 
gelatinous  cyst  is  secreted,  like  the  outer  layer  of  a  solitary  cyst. 
Each  individual  within  the  gelatinous  common  cyst  secretes  a 
membrane,  which  is  thrown  into  wrinkles,  so  that  in  optical 
section  it  looks  as  if  made  of  spicules  joined  together.  These 
cysts  lie  in  pairs  within  the  common  jelly,  the  two  members  of  a 
pair  in  contact  (Fig.  3).  The  nucleus  of  each  cyst  now  goes 
through  a  mitosis  (infra,  pp.  25,  27),  which  results  in  the  extrusion 
of  a  single  polar  body.  When  the  pronuclei  of  a  pair  of  adjacent 
cysts  have  returned  to  the  resting  condition,  the  walls  of  the  cysts 
break  down  at  the  point  of  contact,  the  two  cell-bodies  fuse,  their 
pronuclei  also  fusing,  and  the  completed  zygote  becomes  spheroidal 
within  the  membrane  derived  from  the  cyst -walls  of  the  two 
gametes.  After  a  period  of  quiescence  the  nucleus  of  the  zygote 
divides  into  two,  by  a  process  identical  with  that  observed  in 
asexual  cysts,  and  the  division  of  the  nucleus  is  followed  by  that 



of  the  cell-body  and  of  the  cyst-wall.  On  emerging  from  the  cyst, 
after  division,  vacuoles  and  psetidopodia  are  developed,  and  the 
adult  condition  is  assumed. 

The  majority  of  the  higher  Heliozoa  resemble  Adinophrys  in 
general  structure,  though  their  appearance  may  be  greatly  altered 
by  the  presence  of  a  skeleton  or  by  the  formation  of  a  stalk. 

The  modifications  of  the  cell-body  are  chiefly  those  connected  with 
the  greater  or  less  development  of  vacuoles  and  of  various  coloured 
substances.  The  division  into  ectoplasm  and  endoplasm  is  generally 
obvious.  The  ectoplasm  usually  contains  contractile  vacuoles,  which 


Adinophrys  sol.  I,  two  free-swimming  individuals  in  conjugation.  II,  the  same  individuals 
in  an  early  phase  of  encystment.  The  nuclei  are  considerably  enlarged.  Ill,  formation  of 
the  polar  spindles.  IV,  stage  with  two  reduced  nuclei  and  degenerating  polar  nuclei.  V, 
the  reduced  nuclei  have  fused  together  and  the  polar  nuclei  have  reached  the  periphery. 
VI,  the  first  segmentation  spindle  is  formed  and  the  polar  nuclei  are  ejected  as  polar  bodies. 
i/-,  cyst  membrane;  e.v,  contractile  vacuoles;  N,  nuclei;  P.N,  polar  nuclei;  P.B,  polar 
bodies  ;  P.Sp,  polar  spindle  ;  S.Sp,  segmentation  spindle.  (After  Schaudinn.) 

may  be  very  numerous  (more  than  20  in  Acanthocystis).  In 
Actinosphaerium  the  system  of  non-contractile  vacuoles  is  even  more 
highly  developed  than  in  Adinophrys,  but  in  the  skeletogenous  genera 
the  non-contractile  vacuoles  are  few.  The  ectoplasm  is  usually  the 
seat  of  digestion  and  assimilation,  as  it  is  in  Adinophrys ;  and  usually 
contains  refringent  granules,  which  may  be  rounded,  like  those  of 
Adinophrys,  or  crystalloid  (Heteropkrys).  Perhaps  the  larger  coloured 
granules  which  occur  either  in  the  ectoplasm  or  in  the  endoplasm,  or 
scattered  throughout  the  body,  belong  to  a  different  category  from 
the  refringent  granules  ;  large  brown  granules  may  occur  in  the 
ectoplasm  (Pinacocystis),  brownish  or  yellowish  bodies  may  be  scattered 


through  the  whole  substance  of  the  body  (Pompholyxophrys,  Rliaphi- 
diophrys),  and  in  a  few  forms  (Elaeorhanis)  a  large  coloured  oil 
globule  is  found  in  the  endoplasm.  In  Actinosphaerium,  where 
digestion  and  assimilation  occur  in  the  endoplasm,  that  region  of  the 
body  is  crowded  with  brownish  refringent  granules,  leaving  the  ecto- 
plasm relatively  free.  A  few  of  the  larger  coloured  droplets  have 
been  described  as  fatty ;  but  the  chemical  nature  of  most  of  these 
coloured  bodies  is  quite  unknown. 

Chlorophyll  associated  with  differentiated  chloroplasts  is  found 
either  in  the  endoplasm  (some  varieties  of  Actinosphaerium  Eichhornii) 
or  in  the  ectoplasm  (Rhaphidiophrys,  Heterophrys,  etc.).  The  nature  and 
origin  of  these  bodies  have  been  much  debated  ;  some  writers  have 
regarded  them  as  the  remains  of  green  animals  or  plants  ingested 
as  food ;  Archer  and  Greeff  maintained  that  they  were  in  many 
cases,  at  least,  formed  by  the  Heliozoa  in  which  they  were  observed. 
There  can  be  little  doubt,  however,  that  they  are  in  some  cases  at 
least  of  the  same  nature  as  the  Xanthellae  that  occur  in  Radiolaria 
(see  p.  97)  and  in  Trichosphaerium  among  the  Lobosa,  and  that 
they  are  therefore  independent  organisms  living  in  association  with 
the  Heliozoa,  and  are  not,  as  has  been  suggested,  of  endogenous  origin. 
Although  we  have  at  present  very  little  information  concerning  the 
history  of  these  organisms  in  the  Heliozoa,  the  observations  of 
Penard  on  green  varieties  of  Actinosphaerium  lend  strong  support 
to  this  suggestion.  This  author  found  that  the  green  cells  are  oval 
in  shape,  7-10  //,  in  length,  and  surrounded  by  a  clear  gelatinous 
membrane.  They  possess  a  bell-shaped  chromatophore,  a  spherical 
pyrenoid,  and  in  some  cases  a  vacuole  at  one  end.  On  crushing 
the  Actinosphaerium,  these  cells  escape,  and  subsequently  protrude 
first  one  and  then  a  second  very  delicate  flagellum.  He  believes 
the  organism  to  be  identical  with  the  Palmellacean  Alga  Sphaero- 
cystis  Schroteri  (Chodat).  In  other  cases  he  has  seen  a  large  number 
of  flagellate  organisms  belonging  to  the  genus  Chlamydomonas 
attached  to  the  surface  of  an  Actinosphaerium,  and  has  shown  that 
they  are  actively  attracted  to  the  host.  It  is  true  that  at  present 
it  has  not  been  proved  that  the  Chlamydonionads  actually  enter  the 
ectoplasm  of  the  Actinosphaerium  and  become  the  xanthellae  ;  but  in 
view  of  the  proof  recently  published  by  Keeble  and  Gamble  (10), 
that  the  infecting  organism  of  the  Turbellarian  Convoluta  belongs  to 
the  Chlamydomonadina,  Penard's  observation  is  very  suggestive. 
Awerinzew  (1)  has  recently  described  the  xanthella  of  Actino- 
sphaerium as  Zoochlorella  actinosphaerii. 

In  addition  to  the  xanthellae,  other  organisms  are  occasionally 
found  in  the  ectoplasm  of  the  Heliozoa.  Thus,  a  eiliate  infusorian 
allied  to  the  genus  Blepharisma  has  been  found  in  as  many  as 
30  per  cent  of  the  individuals  of  Rhaphidiophrys  viridis  found  at 
Bernex,  and  a  rotifer  attributed  to  the  genus  Monolabis  by  Archer 


and  to  the  genus  Proales  by  Penard  occurs  in  the  ectoplasm  of 
Acanthocystis  turfacca.  It  is  probable  also  that  the  minute  rods 
that  have  been  found  in  Acanthocystis  turfacea  (Leidy)  and  the 
corpuscles  in  A.  spinifera,  Rhaphidiophrys  viridis,  and  Heterophrys 
myriopoda  may  be  bacteria. 

The  structure  of  the  pseudopodia  is  probably  very  constant  in  all 
the  higher  forms.  In  Elaeorhanis,  Nudearia,  and  Hedriocystis  there 
appears  to  be  no  axial  filament.  In  Clathrulina  elegans  and  in 
Elaeorlumis  they  are  sometimes  bifurcated.  In  a  Heliozoon  allied 
to  Adinophrys,  Crawley  (5)  has  recently  observed  that  the  pseudo- 
podia  are  arranged  in  tufts  at  the  periphery,  and  may  either 
remain  stiff  and  motionless  like  the  typical  pseudopodia  of  Heliozoa 
or  assume  lashing  movements  like  flagella  or  cilia.  In  Adino- 
Sj'hacrium  arachnoid-eum,  Penard,  the  pseudopodia  are  very  long, 
branching,  and  capable  of  anastomoses. 

The  relation  of  the  inner  ends  of  the  axial  filaments  of  the 
typical  pseudopodia  varies  in  a  remarkable  way  with  variation  in 
the  position  of  the  nucleus.  In  Actinosphaerium,  where  the 
number  of  nuclei  is  very  great  (sometimes  over  400),  the  axial 
fibres  end  each  in  the  neighbourhood  of  a  nucleus,  if  not  in  actual 
contact  with  its  membrane,  so  that  the  relation  is  here  similar  to 
that  of  Adinophrys.  In  a  great  number  of  genera,  however,  the 
centre  of  the  body  is  occupied  by  a  deeply-staining  granule  first 
discovered  by  Grenacher  (6)  and  now  known  to  behave  like  a 
centrosome ;  to  this  body  the  inner  ends  of  the  axial  filaments  are 
attached  (Fig.  6,  A).  There  is  never  more  than  a  single  centrosome, 
which  may  be  associated  with  a  single  eccentrically-placed  nucleus 
(Acanthocystis,  etc.)  or  with  many  nuclei  (Gymnosphaera). 

Skeletal  investments  of  several  kinds  are  found  among  the  higher 
Heliozoa.  In  Elaeorhanis  the  body  is  covered  by  an  agglutina- 
tion of  diatoms,  sand-grains,  etc.,  loosely  cemented  together ;  in 
Heterophrys  (Fig.  2  (3))  the  body  is  surroupded  by  a  finely  granular, 
transparent  capsule,  of  gelatinous  consistency  and  quite  unknown 
composition,  soluble  in  strong  acids ;  this  capsule  is  separated  from 
the  ectoplasm  by  a  considerable  space,  traversed  only  by  the  radial 
pseudopodia,  which  emerge  through  perforations  in  its  substance. 
The  outer  surface  of  the  capsule  bears  delicate  radial  spines,  shorter 
than  the  pseudopodia,  which  are  regarded  by  Penard  as  being 
chitinous  in  composition  on  the  ground  that  they  are  soluble  in 
boiling  sulphuric  acid.  In  Actinolophus  the  greater  part  of  the 
body  is  naked,  except  for  a  short  time  before  encystment ;  but  the 
stalk,  on  which  the  body  rests,  is  a  tube  of  what  appears  to  be 
chitin,  containing  one  or  two  thread-like  prolongations  of  the  body. 
The  greater  number  of  skeletons  are,  however,  siliceous,  the  silica 
being  deposited  in  the  form  of  separate  or  loosely-articulated  plates 
or  spicules  (Chalarothoraca)  or  as  a  continuous  basketwork  (Desmo- 


thoraca).  In  the  Chalarothoraca  the  siliceous  particles  may  be 
minute  and  spherical,  lying  close  together  and  forming  one  or 
several  layers  (Pompholyxophrys),  or  they  may  be  elongated  spicules, 
or  flattened  plates.  Spicules  are  of  two  kinds,  the  one  kind  curved 
and  pointed  at  each  end,  the  other  straight,  pointed  or  bifurcate  at 
one  end,  flattened  and  expanded  at  the  other.  The  curved  spicules 
are  placed  tangentially  to  the  surface  of  the  body,  and  may  be  the 
only  skeletal  elements  present  (Ithaphidiophrys),  in  which  case  they 
form  a  loose  investment  for  the  animal,  from  which  groups  of 
spicules  are  occasionally  carried  up  the  pseudopodia  by  the 

FIG.  4. 

Heterophrys  Fockei,  Archer,  c.c,  contractile  vacuoles.  A  nucleus  is  present  in  the  centre 
of  the  protoplasm,  but  is  not'shown  in  the  figure,  s,  radial  chitinous (?)  spines  surrounding 
the  envelope.  Several  xanthellae  are  seen  in  the  protoplasm.  (After  Hertwig  and  Lesser.) 

streaming  movement  of  the  ectosarc  (Fig.  2  (4)).  In  lihaphidocystis 
some  very  remarkable  funnel-shaped  or  wine-glass-shaped  spicules 
are  found.  In  Acanthocystis  both  tangential  scales  and  straight 
spicules  may  be  present,  the  latter  being  radially  placed,  with  their 
pointed  ends  outwards.  There  may  be  two  kinds  of  these  radial 
spicules,  a  longer  hollow  kind  with  the  free  extremity  bluntly 
pointed,  and  a  shorter  solid  kind  with  the  free  end  forked  (Fig.  2  (5)). 
Siliceous  plates,  articulated  together  by  their  edges  to  form  a 
capsule  round  the  body,  occur  in  Pinacocystis  and  in  Pinaciophora. 
In  Pinacocystis  the  pseudopodia  emerge  through  the  spaces  between 
the  plates,  but  in  Pinaciophora,  according  to  Greeff,  the  plates  are 
perforated  by  fine  pores. 


In  the  Desmothoraca,  of  which  Clathrulina  is  the  best-known 
genus,  the  skeleton  has  the  form  of  a  spherical  basketwork,  the 
bars  of  which  often  show  a  median  ridge  on  the  outer  surface,  the 
spaces  between  the  bars  being  irregularly  polygonal  with  rounded 
angles  (Fig.  2  (2)).  This  basketwork  is  supported  on  a  long,  hollow 
.siliceous  stalk. 

The  structure  of  the  nucleus  and  the  processes  of  hiryolcinesis 
have  been  minutely  described  by  R.  Hertwig  (8)  in  Actinosphaerium, 
and  his  descriptions  are  in  accord  with  what  is  known  concerning 
them  in  the  higher  Heliozoa  generally. 

The  resting  nucleus  of  Actinosphaerium  has  a  definite  membrane 
.continuous  with  an  internal  achromatic  network  whose  relation  to 
the  chromatin  elements  is  very  variable.  The  whole  of  the 
.chromatin  may  be  collected  into  a  relatively  large  mass,  supported 
in  a  matrix  of  achromatic  substance  ("plastin")  and  forming  a 
conspicuous  "  karyosomatic "  nucleolus ;  such  a  condition  of  the 
nucleus  may  be  induced  by  starvation,  or  it  may  appear  as  a  pre- 
liminary to  division.  In  well-fed  individuals  the  chromatin  spreads 
through  the  nucleus  in  the  form  of  coarse  branches  or  networks. 

Nuclear  division  may  be  direct,  in  the  formation  of  buds  or 
swarm -spores,  or  by  karyokinesis.  Karyokinesis  occurs  in  the 
division  of  the  nuclei  within  the  body  of  the  multinucleate  forms 
(e.g.  Actinosphaerium)  without  being  followed  by  division  of  the 
body ;  in  forms  with  a  single  nucleus  it  occurs  during  fission,  and 
during  the  maturation  of  the  conjugants  (gametocytes). 

In  Actinosphaerium  there  are  three  kinds  of  karyokinesis,  that 
differ  from  each  other  in  some  details  of  considerable  theoretical 
importance.  In  the  nuclear  divisions  of  the  unencysted  body  no 
£entrosomes  are  formed,  and  the  spindle  is  considerably  compressed 
between  the  two  poles.  In  both  the  mitoses  of  the  maturation  of  the 
gametocytes,  centrosomes  occur  at  each  pole  of  the  spindle,  but  in 
the  first  (polar)  division  the  chromosomes  are  larger  than  in  the  second 
.(polar)  division,  and  there  are  some  other  differences  in  detail  of 
minor  importance.  In  all  three  kinds  of  karyokinesis  there  are 
numerous  chromosomes  (about  150),  and  both  the  divisions  of  the 
nuclei  in  the  maturation  of  the  gametocytes  are  of  the  nature  of  "equa- 
tion "  divisions,  the  number  of  the  chromosomes  not  being  reduced. 

It  may  be  convenient  to  describe  in  greater  detail  the  second 
polar  division  of  Actinosphaerium  as  an  example  of  the  karyokinesis 
of  the  Heliozoan  nucleus.  At  the  end  of  the  first  polar  division, 
one  of  the  resultant  nuclei  degenerates  and  is  ultimately  ejected 
with  the  first  polar  body,  the  other  remains  in  the  centre  of  the 
protoplasm  and  passes  through  a  short  period  of  rest.  At  one 
pole  of  this  resting  nucleus  there  is  a  clearly-marked  centrosome 
surrounded  by  a  small  aster.  Antecedent  to  the  second  polar 
division  the  centrosome  diminishes  in  size  (Fig.  5,  I,  c),  and 



subsequently  divides  into  two  parts,  which  travel  to  opposite  poles 
of  the  nucleus.  The  nucleus  now  begins  to  increase  considerably 
in  size,  and  is  seen  to  contain  several  large  chromatin  bodies  which 
certainly  contain  both  chromatin  and  plastin  derived  from  the 
nucleoli  (Fig.  5,  II).  The  centrosomes  at  each  pole  of  the 
nucleolus  are  of  considerable  size  and  more  conspicuous  than  at 
any  other  time  in  the  divisions  of  the  three  kinds  of  karyokinesis. 
The  chromosomes  are  now  formed  by  a  breaking  down  of  the 

@\.  . 



~"— -~^c 


*V:-:-  *t~3:i.i.1il 

FIG.  5. 

Actinosphaeriitm.  Formation  of  the  second  polar  spindle.  I,  the  nucleus  after  the  first 
polar  division,  the  centrosome  (c)  reduced  in  size  previous  to  the  formation  of  the  second 
polar  figure.  II,  the  same  nucleus  at  a  later  stage  with  two  centrosomes.  Ill,  IV,  V,  VI, 
VII,  stages  in  the  formation  of  the  second  polar  nucleus.  (After  R.  Hertwig.) 

chromatin  masses,  and  gradually  assume  an  equatorial  position. 
They  are  at  first  very  irregular  and  angular  in  shape,  but  ultimately 
become  rod-shaped,  constrict  in  the  middle,  and  divide  transversely. 
The  spindle  fibres  seem  to  be  formed  from  the  achromatic  network, 
and  several  plastin  remnants  remain  in  the  nucleus  during  ther 
formation  of  the  chromosomes.  The  chromosomes  now  travel 
towards  the  opposite  poles  of  the  spindle  in  the  usual  way 
(Fig.  5,  VI),  and  subsequently  become  arranged  in  a  fan-shaped 
manner  at  the  extremities  of  the  now  elongated  spindle.  According 



to  Hertwig  (8)  the  chromosomes  of  the  second  polar  division  are 
only  half  the  size  of  the  chromosomes  of  the  first  division,  and 
there  is,  therefore,  a  reduction  in  the  mass  of  the  'chromosomes, 
although  there  is  apparently  no  reduction  in  their  number. 

The  karyokinesis  of  the  nuclei  of  the  ordinary  unencysted 
Adinospliaerium  differs  from  that  just  described  principally  in  the 
fact  that  no  centrosomes  are  present.  The  first  sign  of  commencing 
division  in  these  nuclei  is  the  accumulation  of  a  clear  mass  of 
nearly  homogeneous  protoplasm  at  each  pole ;  the  nucleus  becomes 



Fio.  6. 

A,  Acanthocystis  aculeata,  H.  and  L.,  in  the  living  condition,  with  expanded  pseudopodia. 
N,  the  nucleus  ;  c,  the  centrosome.  B,  C,  D,  B,  F,  successive  stages  in  the  mitoticldivision  of 
the  nucleus  as  seen  in  preparations.  (After  Schaudinn.) 

flattened  so  that  the  diameter  which  passes  through  the  proto- 
plasmic masses  is  the  shortest,  and  at  each  end  of  this  diameter  an 
accumulation  of  achromatic  nuclear  substance  is  formed,  giving  rise 
to  what  Hertwig  calls  the  "  polar  plates." 

In  Acanthocystis  the  nucleus  is  situated  excentrically,  and  con- 
sists of  a  central  deeply -staining  body,  the  "  pseudonucleolus," 
surrounded  by  an  area  which  certainly  contains  a  linin  network 
but  much  less  chromatin.  At  the  exact  centre  of  the  endoplasm 
there  is  a  small  body  which  exhibits  radiating  lines  which 
appear  to  extend  outwards  and  be  continuous  Avith  the  axes 
of  the  pseudopodia  (Fig.  6).  This  body,  originally  described  by 



Grenadier  (6)  as  the  "  Centralkorn,"  has  been  proved  by 
Schaudinn  to  be  a  true  centrosome.  It  has  been  discovered  to 
be  a  permanent  of  the  body  in  llhaphidiophrys,  Adinolophus,  Hetero- 
phrys,  and  Sphaerastrum.  Before  division  of  the  nucleus  it  divides 
into  two  equal  parts,  which  take  a  position  at  opposite  poles  of  the 
endoplasm,  each  one  surrounded  by  an  aster  of  radiating  lines.  The 
nucleus  leaves  its  excentric  position  and  becomes  situated  in  a 
direct  line  between  the  two  centrosomes.  The  nuclear  mem- 
brane then  fades  away  and  a  party  of  numerous  small  chromo- 
somes occupy  a  position  of  an  equatorial  band  on  the  spindle  that 

Fio.  7. 

A,  B,  C,  direct  amitotic  division  of  the  nucleus  of  Acanthocystis  aculeata  as  seen  in  the 
process  of  the  formation  of  buds.  U,  a  colony  of  Acanthocystis  formed  by  the  gemmation  of 
a  single  individual.  Only  two  individuals  of  the  colony  exhibit  a  centrosome,  and  these  have 
been  formed  by  division,  with  nuclear  mitosis,  of  the  primary  individuals  ;  the  others  have 
been  formed  by  gemmation  without  nuclear  mitosis.  E,  a  single  bud  freed  from  the 
colony.  F,  a  flagellula.  G,  an  amoeboid  spore.  (After  Schaudinn.) 

is  formed  from  the  linin  of  the  nucleus.  The  subsequent  phases 
of  the  nuclear  division  resemble  those  of  the  typical  karyokinesis 
of  the  metazoan  cell. 

*  In  the  formation  of  the  buds  of  Acantlwcystis  the  nucleus  divides 
directly  and  the  centrosome  remains  unchanged  (Fig.  7,  A,  B). 
The  buds  are  therefore  for  a  time  without  any  centrosome,  but 
this  body  is  formed  afresh  in  the  buds  from  the  nucleus.  (See 
Part  I.  Fasc.  II.  Fig.  20,  p.  41.) 

Reproductive  Processes. — Probably  all  the  higher  Heliozoa  are 
capable  of  fission,  preceded  or  not  by  encystment,  although  the 
process  has  not  been  observed  in  all.  The  division  of  the  nucleus 


is  mitotic,  and  is  probably  of  the  type  observed  in  adult  Actino- 
spliaerium  or  of  that  seen  in  Acanthocystis,  according  to  the  presence 
or  absence  of  a  permanent  centrosome. 

Budding  has  been  observed  in  several  cases ;  and  the  process 
has  lately  been  described  in  detail  by  Schaudinn  (19)  in  Acantho- 
cystis.  The  nucleus  divides  directly  once  or  several  times,  so  that 
the  body  may  contain  a  considerable  number  of  nuclei ;  during 
this  process  the  pseudopodia  are  not  withdrawn,  the  centrosome 
and  the  system  of  axial  filaments  remaining  unchanged.  One  of 
the  nuclei  resulting  from  this  division  remains  in  the  body  of  the 
parent  without  further  change ;  each  of  the  others  travels  into  a 
small  projection  from  the  surface  of  the  body,  which  is  the  future 
bud.  Every  bud  is  covered  with  a  layer  of  spicules  derived  from 
the  parental  skeleton,  but  it  contains  no  centrosome,  nor  any  trace 
of  radial  fibres.  The  buds  so  formed  may  behave  very  differently 
in  different  cases,  and  there  is  at  present  no  knowledge  of  the 
circumstances  which  determine  their  behaviour.  A  bud  may 
separate  from  the  parent  in  the  condition  described,  and  may 
divide  one  or  more  times,  the  products  of  division  going  through  a 
short  resting  stage  before  emitting  pseudopodia ;  or  the  resting 
stage  may  occur  immediately  after  the  bud  leaves  the  parent,  in 
which  case  it  does  not  divide  before  assuming  the  adult  condition. 
In  these  cases  there  is  nothing  like  "  spore-formation  " ;  but  a  bud 
may  become  amoeboid,  and  creep  out  of  its  skeletal  investment, 
either  before  the  skeleton  has  separated  from  the  parent  or 
immediately  afterwards ;  and  such  an  amoebula  may  creep  about 
for  a  day  or  two,  by  means  of  blunt  pseudopodia,  before  it  becomes 
spherical  and  secretes  new  spicules  ;  or,  division  of  the  nucleus  may 
occur  within  the  bud,  so  that  several  amoebulae  leave  it,  instead  of 
one.  Lastly,  an  amoebula,  at  the  moment  of  leaving  the  parental 
skeleton  or  soon  afterwards,  may  develop  two  flagella,  by  means  of 
which  it  swims  for  a  short  time ;  such  "  flagellulae "  quickly 
become  amoeboid  and  creep  about  for  a  further  period  as  amoe- 
bulae, before  becoming  spherical.  None  of  these  buds  or  spores  are 
known  to  conjugate,  and  indeed  the  origin  of  sexual  spores  by  an 
amitotic  division  would  be  remarkable  ;  but,  however  they  behave  in 
the  meantime,  about  the  fourth  or  fifth  day  after  emission  each  of 
them  becomes  spheroidal,  and  secretes  a  skeleton  of  small  tangential 
spicules,  which  are  first  formed  in  the  immediate  neighbourhood  of 
the  nucleus,  and  afterwards  travel  to  the  periphery.  The  centro- 
some arises  from  the  nucleus  (Part  I.  Fasc.  II.  Fig.  20,  p.  41),  and 
after  it  is  established  the  axes  of  the  radial  pseudopodia  appear. 

The  formation  of  "swarm -spores"  was  first  described  by 
Cienkowski  (4)  in  Clathrulina ;  it  was  more  recently  discovered  by 
Schaudinn  (19)  in  Acanthocystis ;  and  it  may  occur  in  Adinophrys 


Sexual  (karyogamic)  processes  have  only  been  observed  in 
Actinophrys  and  in  Actinosphaerium ;  the  process  in  Actinophrys 
has  already  been  described  ;  the  phenomena  observed  in  Actino- 

Actinosphaerium.  A,  a  mother-cyst  just  before  it  breaks  up  into  primary  cysts.  The 
nuclei  are  considerably  reduced  in  number  and  the  protoplasm  contains  numerous  small 
oval  yolk-plates,  y.p.  B,  the  primary  cysts  have  each  divided  into  two  secondary  cysts.  The 
sister-cyst  of  a  is  not  seen  in  the  figure.  N,  nuclei  ;  c.m,  mother-cyst  membrane  ;  c.m%,  cyst 
membrane  of  the  first  order.  (After  Brauer.) 

sphaerium  are  in  many  ways  remarkably  different.  The  first  indica- 
tion of  approaching  karyogamy  is  the  encystment  of  a  single 
individual.  The  pseudopodia  are  withdrawn,  their  axial  filaments 


are  absorbed,  and  the  animal  sinks  to  the  bottom  of  the  water, 
where  it  exhibits  considerable  amoeboid  movement,  sometimes 
giving  out  slender  pointed  pseudopodia  which  have  no  axial 
filaments ;  food-particles  are  ejected,  and  a  thick,  transparent  cyst 
is  formed.  This  "  mother-cyst  "  is  of  gelatinous  consistence,  sticky 
on  the  outside,  and  its  substance  is  deposited  in  concentric  layers. 
The  peripheral  vacuoles  disappear  after  encystment,  and  numerous 
peculiar  oval  discs,  probably  consisting  of  reserve  food- material, 
appear;  these  bodies  may  be  called  "yolk-plates"  (Hertwig). 
While  the  yolk -plates  are  forming,  the  number  of  the  nuclei 
diminishes,  until  not  more  than  one -twentieth  of  the  original 
number  remain.  The  process  by  which  this  reduction  is  effected 
is  not  quite  clear;  Schneider  and  more  recently  Brauer  (2) 
have  described  a  fusion  of  nuclei  during  the  reduction;  and 
Brauer's  figures  of  this  fusion  are  very  convincing ;  Hertwig, 
although  he  considers  it  not  improbable  that  such  a  fusion  occurs, 
has  never  been  able  to  demonstrate  it.  When  the  reduction  in  the 
number  of  nuclei  is  completed,  the  body  divides  into  as  many 
pieces  as  there  are  nuclei,  each  piece  containing  a  single  nucleus. 
Every  result  of  this  division  is  enclosed  in  a  siliceous  "  primary 
cyst,"  largely  formed  by  rearrangement  of  scattered  spicules 
secreted  before  division.  The  number  of  primary  cysts  varies 
from  one  to  thirty-five ;  and  Smith  (20)  has  recently  shown 
that  there  is  an  interesting  relation  between  the  number  formed 
and  the  temperature  at  which  encystment  occurs ;  at  high  tempera- 
tures the  number  is  smaller  and  the  cysts  are  larger ;  at  low 
temperatures  the  number  of  cysts  is  greater  and  their  diameter 
less.  Smith  also  shows  that  the  quantity  of  chromatin  contained 
in  the  nuclei  of  primary  cysts  formed  at  a  low  temperature  is 
greater  than  that  found  in  cysts  formed  at  higher  temperatures. 
Shortly  after  its  formation,  each  primary  cyst  divides  into  two; 
the  nucleus  behaves  in  essentially  the  same  way  as  dividing  nuclei  in 
the  unencysted  form  (cf.  p.  25)  ;  the  number  of  chromosomes  is  very 
large,  and  is  estimated  by  Hertwig  at  from  130  to  150.  The 
secondary  cysts,  formed  by  the  division  of  each  primary  cyst,  now 
behave  like  gametocytes ;  a  centrosome  is  extruded  from  the 
nucleus,  and  a  nuclear  division  occurs,  leading  to  the  extrusion  of  a 
first  polar  body.  After  the  extrusion  of  the  first  polar  body,  the 
nucleus  enters  into  a  resting  stage,  a  single  centrosome  remaining 
outside  it ;  a  second  division  now  occurs,  leading  to  the  formation 
of  a  second  polar  body,  which  is  in  turn  extruded.  The  chief 
points  of  interest  in  the  formation  of  the  polar  bodies  are  (1)  the 
similarity  of  the  process  of  formation,  so  that  neither  division  can 
'be  called  a  "reducing  division";  and  (2)  the  very  pronounced 
resting  stage  which  intervenes  between  them. 

After  the   extrusion    of   the  polar   bodies,   the    two    gametes, 

32  .    THE  HELIOZOA 

formed  from  the  products  of  the  division  of  a  single  primary  cyst, 
fuse  again  into  a  single  zygote,  their  pronuclei  uniting  to  form  a 
single  fertilised  nucleus.  After  this  process  is  completed,  a 
membranous  or  gelatinous  layer  is  formed  within  the  siliceous 
cyst,  which  Hertwig  compares  to  the  yolk-membrane  so  frequently 
formed  by  fertilised  ova.  A  multiplication  of  nuclei  now  occurs 
within  the  cyst ;  the  creature  becomes  amoeboid,  and  emerges. 
After  emergence,  individuals  with  a  single  nucleus  are  not  very 
rare,  so  that  the  amoeboid  young  may  possibly  sometimes  divide ; 
but  the  process  has  not  been  observed. 

If  the  foregoing  account  be  correct,  we  have  in  Actinosphaerium 
the  only  case  in  the  whole  animal  kingdom  in  which  self-fertilisa- 
tion is  shown  to  be  of  normal  occurrence.  There  are,  however, 
several  points  to  be  considered  before  this  view  can  be  adopted 
without  qualification.  Brauer  (2)  asserts  that  the  formation  of 
Hertwig's  "  primary "  cysts  is  preceded  by  a  fusion  of  nuclei,  so 
that  the  nucleus  of  each  primary  cyst  is  really  formed  from  two 
resting  nuclei,  confirming  the  view  put  forward  by  Anthon  Schneider 
in  1877  ;  and  Hertwig  admits  that  there  is  a  considerable  body 
of  evidence  in  favour  of  this  view,  though  if  such  a  fusion  takes 
place  it  must  be  a  very  rapid  process,  affecting  all  the  nuclei 
in  the  body  simultaneously ;  otherwise  its  occurrence  must  have 
been  frequently  witnessed  by  an  observer  so  skilful  and  patient 
as  Professor  Hertwig.  The  frequent  occurrence  of  plastogamy 
between  adult  individuals  makes  it  very  possible  that  all  the  nuclei 
in  the  same  body  may  not  be  of  the  same  origin ;  and  therefore 
the  formation  of  the  primary  cyst- nuclei  by  the  fusion  of  two 
others  might,  in  many  cases,  at  least,  mean  the  fusion  of  nuclei 
originally  produced  in  different  individual  bodies  (Schaudinn). 
Such  a  preliminary  fusion  of  the  nuclei  of  gametocytes,  which 
separate  before  giving  off  polar  bodies  and  finally  fusing  to  form 
a  zygote  nucleus,  has  been  observed  in  Spirogyra  (cf.  Klebahn  [11], 
quoted  by  Hertwig) ;  and  a  process  of  a  similar  kind — a  fusion 
of  gametocyte  nuclei  before  the  extrusion  of  polar  bodies,  the  polar 
bodies  being  only  given  off  after  division  of  the  fertilised  zygote — 
appears  to  occur  in  some  desmids  (Closterium,  Klebahn  [11]).  If, 
therefore,  we  can  believe  that  an  individual  before  encystment  has 
normally  exchanged  some  of  its  nuclei  for  those  of  another  indi- 
vidual during  an  antecedent  plastogamy,  and  that  a  fusion  of  nuclei 
in  pairs  takes  place  before  the  formation  of  the  "primary"  cysts, 
the  nuclear  history  of  Actinosphaerium  will  not  be  without  parallel ; 
but  there  is  direct  evidence  that  normal  encystment  may  occur 
without  plastogamy,  since  Hertwig  has  succeeded  in  keeping  an 
isolated  individual  under  control  through  the  entire  period  from 
"  hatching  "  until  the  production  of  normal,  fertile  cysts.  Again, 
all  observers  are  agreed  that  plastogamy  is  not  necessarily  followed 


by  encystment  Avithin  any  definite  period,  and  Hertwig  has  obtained 
cysts  from  individuals  in  which  it  had  certainly  not  occurred  for 
several  weeks. 

ORDER  1.  Aphrothoraca,  Hertwig. 

Heliozoa  usually  devoid  of  a  skeletal  or  gelatinous  envelope.  A 
membranous  envelope,  sometimes  with  siliceous  spicules,  is  only  developed 
during  encystment. 

Genera — Actinophrys,  Ehrb.  ca.  50  p.  Cosmopolitan  in  fresh  water 
and  probably  cosmopolitan  in  the  sea  (Fig.  2).  Camptonema,  Schaud. 
Numerous  small  contractile  vacuoles  and  about  50  nuclei.  120-180  p.. 
Marine,  Norway.  Actinosphaerium,  Stein  (Fig.  1).  Two  or  more  large  con- 
tractile vacuoles,  numerous  nuclei.  1  mm.  Cosmopolitan  in  fresh  water. 
Gymnosphaera,  Sassaki.  Numerous  nuclei.  Very  numerous  and  very  long 
pseudopodia.  140  /x.  Pseudopodia  up  to  800  p.  in  length.  Actinolophus, 
F.  E.  Schultze.  Body  usually  pear-sheaped.  One  nucleus.  Pseudopodia 
long  and  thin.  Sometimes  (always  t)  with  a  thin  gelatinous  membrane 
perforated  by  the  pseudopodia.  Attached  to  a  foreign  object  by  a  long 
hollow  stalk.  Body  30  p.  in  diameter.  Stalk  100  p,  long  by  3-4/4  in 
diameter.  Marine.  North  Sea.  The  genus  Actinosphaeridium,  Zacharias, 
freshwater,  Germany,  is  closely  related  to  Actinolophus.  The  genera 
Zooteirea,  Wright,  an  oval  form  with  a  contractile  stalk,  from  the 
Firth  of  Forth,  EstrMa,  Frenzel,  and  Phythelius,  Frenzel,  are  imper- 
fectly known.  Phythelius  is  probably  an  Alga.  Nuclearia  (see  p.  8), 
Cienkowski,  differs  from  the  other  Heliozoa  in  having  an  amoeboid 
body  and  pseudopodia  without  any  definite  axis.  It  is  sometimes 
regarded  as  a  Proteomyxan.  Myxodiscus  crystalligerus  is  a  form  that  is 
doubtfully  placed  among  the  Heliozoa.  It  was  found  by  Prowazek  in  a 
sea-water  aquarium.  The  genus  Archerina,  Lankester,  which  has  been 
regarded  by  some  authors  as  a  Proteomyxan  and  by  others  as  a  Heliozoon, 
is  now  placed  by  Lankester  (1 2)  among  the  Algae.  It  is  the  same  genus  as 
Golenkinia  (Chodat.),  belonging  to  the  Pleurococcaceae,  the  naked  proto- 
plasm surrounding  the  green  organism  in  many  instances  observed  and 
figured  by  Lankester  being  that  of  a  Vampyrella-like  or  amoeboid 
organism  symbiotic  with  or  merely  crawling  on  the  alga. 

ORDER  2.  Chlamydophora,  Archer. 

Heliozoa  with  a  soft  mucilaginous  envelope,  but  without  any  solid 
skeletal  elements. 

Astrodisculus,Greeft  (Fig.  2(8)).  Body  spherical.  Pseudopodia  very  long 
and  delicate.  Several  species  recently  described  by  Penard.  Freshwater. 
20-40  p.  The  genus  Heliophrys,  Greeff,  is  evidently  closely  related  to 
Astrodisculus,  but  has  also  been  placed  with  Heterophrys  (see  West  [21]). 
The  form  described  by  Greeff  as  Chondropus  viridis  is  regarded  by  Penard 
as  a  peculiar  species  of  Vampyrella, 



ORDER  3.   Chalarothoraca,  Hertwig  and  Lesser. 

Heliozoa  with  a  loose  envelope  consisting  of  isolated  siliceous  or 
chitinous  spicules  bound  together  by  a  mucilaginous  or  protoplasmic 

Heterophrys,  Archer  (Figs.  2  (3)  and  4).  A  granular  envelope  containing 
very  delicate  and  indistinct  chitinous  spicules.  One  nucleus  and  one  or  more 
contractile  vacuoles.  10-20  p..  Freshwater  (or  marine  ?).  Sphaerastrum, 
Greeff.  According  to  Penard  (14)  this  genus  represents  a  species  of 
Rhaphidiophrys.  Elaeorhanis,  Greeff.  The  endoplasm  contains  a  large 
yellow  or  brown  oil -globule.  Envelope  with  attached  sand -grains  and 
diatoms.  50  /*.  Freshwater.  Lithocolla,  F.  E.  Schultze.  No  definite 
oil-globule.  Envelope  with  numerous  siliceous  bodies,  for  the  most  part 
adventitious  diatoms,  and  amorphic  grains.  Often  united  together  in 
colonies  by  a  gelatinous  matrix.  38-45  p-.  Freshwater  and  marine. 
Lithosphaerella,  Frenzel.  Envelope  covered  with  several  layers  of  sand- 
grains.  Freshwater  (Argentine)  and  marine  (Mediterranean).  All  the 
genera  so  far  mentioned  were  placed  by  Schaudinn  (18)  and  others  in  the 
Order  Chlamydophora,  but  were  transferred  to  the  Order  Ohalarothoraca 
by  Penard. 

The  following  genera  have  isolated  siliceous  skeletal  spicules  and 
are  regarded  as  more  typical  of  the  Order.  Pompholyxophrys,  Archer  = 
Hyalolampe,  Greeff.  Skeleton  composed  of  minute  spherical  pearls  of 
silex.  40-50  JJL.  Freshwater.  Pinaciophora,  Greeff.  Skeleton  con- 
sisting of  overlapping  circular  plates.  50  p..  Freshwater.  The  genus 
Pinacocystis,  H.  and  L.,  which  is  said  to  be  marine,  is  closely  related  to 
Pinaciophora.  Rhaphidiophrys,  Greeff  (Figs.  2  (4)  and  9).  Skeleton  consist- 
ing of  a  number  of  minute  needles,  spindles  or  half-rings  arranged  loosely, 
tangentially,  and  radially  in  a  protoplasmic  envelope.  This  genus  con- 
tains several  species  and  is  widely  distributed  in  fresh  water.  It  is 
often  found  in  colonial  groups.  Freshwater  and  marine  (A.  pelagica, 
Ostenfeld  [13]).  Rhaphidocystis,  Penard.  Spicules  of  various  forms,  but 
always  different  from  those  of  Rhaphidiophrys,  scattered  in  a  protoplasmic 
envelope.  12-20  /JL.  Freshwater.  R.  simplex  =  Acanthocystis  simplex, 
Schaudinn.  Central  Africa.  Acanthocystis,  Carter  (Figs.  2  (5)  and  6). 
The  envelope  of  siliceous  spicules  apparently  continuous,  formed  of 
tangential  scales  apparently  touching  one  another  and  an  armature  of 
radial  needles.  This  genus  contains  a  large  number  of  species,  widely 
distributed  in  fresh  water.  Two  species,  A.  italica  and  A.  marina 
(Ostenfeld),  are  marine.  The  genera  Cierikowskia,  Schaudinn,  and 
Wagnerella,  Meresch.,  from  the  White  Sea,  differ  from  the  others  in 
the  possession  of  a  stalk. 

ORDER  4.  Desmothoraca,  Hertwig  and  Lesser. 

Heliozoa  provided  with  a  continuous  basket-like  skeleton  perforated 
by  holes. 

Clathrulina,  Cienkowski  (Fig.  2  (2)).  Apertures  in  skeleton  relatively 
large.  Provided  with  a  stalk.  70  /z.  Freshwater.  Hedriocystis,  H. 



and  L.  Apertures  very  small.  Provided  with  a  stalk.  20-30  \L.  Fresh- 
water. Elaster,  Grimm.  Apertures  very  numerous.  No  stalk.  20  p. 
Freshwater.  Choanocystis,  Penard.  Apertures  provided  with  long  funnel- 
shaped  collars.  No  stalk.  13  p..  Freshwater. 

Fio.  0. 

Rhaphidiophrys  elcgans.  Eight  individuals  united  together  by  protoplasmic  strands  and 
surrounded  by  a  skeleton  of  half- rings.  A  nucleus  is  shown  in  one  individual.  (After 
Jlertwig  and  Lesser.) 


A  very  extensive  list  of  works  on  Heliozoa  will  be  found  in  the  book  by 
Fenard  (14).  The  following  is  a  list  of  some  of  the  priucipal  books  and  papers 
referred  to  in  the  text : — 

1.  Awerinzew,  S.      0  zookhlorellakl  u  Prostyeishikh  (On  Zoochlorellae  in  the 

Protozoa).     Protok.  St.  Peterb.  Obshch.  xxxi.  1,  No.  7  (1900),  p.  322. 

2.  Brauer,  A.     Zeitschr.  wiss.  Zool.  Iviii.  (1894),  p.  189. 

3.  Biitschli,  0.     Bronn's  Thierreich,  Protozoa,  1880-82.     This  contains  a  biblio- 

graphy up  to  the  year  1879. 

4.  Cienkowski,  L.     Arch,  inikr.  Anat.  iii.  (1867). 

5.  Crawley,  S.     P.  Ac.  Philad.  54  (1902),  p.  256. 

6.  Grenadier,  H.     Z.  wiss.  Zool.  v.  (1869),  p.  259. 

7.  Hertwig,  R.,  and  Lesser,  E.     Arch.  mikr.  Anat.  x.  (1874),  Supp. 

8.  Hertwig,  R.     Abh.  k.  bayer.  Akad.  Wiss.  xix.  (1898). 
9. Test,  von  Haeckel  (1904). 

10.  Keeble,  F.,  and  Gamble,  F.   W.     Quart.  J.  Micr.  Sci.  li.  (1907),  p.  167. 

11.  Klebahn,  H.     Jahrb.  wiss.  Bot.  xxii.  (1890),  p.  415. 


12.  Lankester,  E.  R.     On  Archerina,  Golenkinia,  and  Botryococcus.     Quart.  J. 

Micr.  Sci.  lii.  (1908),  p.  423. 

13.  Ostenfeld,  C.  H.     Meddel.  Komm.  Havundersog.  Kobenhavn. 

14.  Penard,  E.     Heliozoaires  d'eau  douce.     Geneve  (1904). 

15.  Prowazek,  S.  von.     Arb.  Inst.  Wien,  xii.  (1900),  p.  294. 

16.  Schaudinn,  F.     S.  B.  Ak.  Berlin  (1894),  (2),  p.  1277.     (Camptonema.) 

17.  Ibid.  (1896),  v(l),  p.  83. 

18.  Das  Tierreich.     Heliozoa  (1896). 

19.  Verb,  der  deutscb.  zool.  Ges.  Bonn,  vi.  (1896),  p.  113. 

20.  Smith,  G.     Biometrica,  vol.  ii.  (1902),  p.  3. 

21.  West,  G.  S.     J.  Linn.  Soc.  xxviii.  (1901),  p.  308. 
'22.  Ibid.  xxix.  (1903),  p.  108. 

THE  PROTOZOA  (continued) 


Div.  I.     ENDOSPOREAE. 


Order  1.  Physaraceae. 
,,      2.  Didymiaceae. 


Order  1.  Stemonitaceae. 
„      2.  Amaurochaetaceae. 


Order  1.  Heterodermaceae. 

„      2.  Liceaceae. 

„      3.  Tubulinaceae. 

,,      4.  Reticulariaceae. 

„      5.  Lycogalaceae. 


Order  1.  Trichiaceae. 
„  2.  Arcyriaceae. 
„  3.  Margaritaceae. 

Div.  II.     EXOSPOREAE. 

Order.  Ceratiomyxaceae. 


Order  1.  G-uttulinaceae. 
„      2.  Dictyosteliaceae. 

By  J.  J.  Lister,  F.R.S.,  Fellow  of  St.  John's  College,  Cambridge. 


THE  plasmodial  and  the  spore-bearing  phases  in  the  life-history  of 
the  Mycetozoa  have  long  been  known.  Many  of  the  generic  names 
date  from  the  eighteenth  century,  and  Fries  enumerated  192 
species  in  1829. 

By  the  earlier  naturalists  these  organisms  were  classed,  under 
the  names  Myxogastres  or  Myxomycetes,  with  the  Gasteromycetous 
Fungi,  to  which  the  sporangia  of  the  Endosporeae  present  in 
miniature  a  considerable  superficial  resemblance.  Although  this 
view  of  their  relationship  is  now  generally  abandoned,  its  influence 
may  be  traced  in  the  names  "  capillitium "  and  "  hypothallus " 
which  are  still  applied  to  structures  present  in  the  spore-bearing 
stages  of  the  Mycetozoa. 

It  was  de  Bary  (1-3)  who  first  worked  out  (1859-64)  the  main 
features  of  the  life-history,  showing  that  the  spore  hatches  out  as 
a  naked  protoplasmic  body  which  assumes  a  flagellate  form,  that 
this  passes  after  successive  divisions  into  an  amoeboid  form,  and 
that  from  the  amoebae  the  large  plasmodia  arise. 

Cienkowski  (7)  contributed  (in  1863)  the  important  observation 
of  the  mode  of  origin  of  the  plasmodia  by  the  fusion  of  the 
amoeboid  swarm-cells. 

De  Bary  showed  how  widely  different,  both  morphologically 
and  physiologically,  these  organisms  are,  not  only  from  the  higher 
fungi,  but  from  all  those  included  in  the  vegetable  kingdom,  and 
clearly  expressed  the  opinion  that  they  should  be  regarded  as 

In  the  discussion  of  the  relationships  of  the  Mycetozoa  which 
followed  the  publication  of  de  Bary's  work,  it  was  early  recognised 
that  some  of  the  simple  organisms  included  in  the  large  and  ill- 
defined  group  of  the  Monadina  present  phases  comparable  with  those 
of  the  Mycetozoa.  Thus  Protomonas  amyli  and  P.  parasitica,  which 
are  parasitic  in  vegetable  tissues  containing  starch,  were  found 
by  Cienkowski  (8)  to  begin  their  development  as  flagellate  swarm- 
cells,  and  then  to  become  amoeboid,  in  which  stage  they  take  in 
or  envelop  starch  grains,  which  they  are  able  to  digest.  Later  they 
encyst ;  the  protoplasm  withdraws  from  the  undigested  food  and 
breaks  up  into  a  fresh  brood  of  swarm-cells.  Moreover,  fusion  of 
several  individuals  may  occur  in  the  amoeboid  stage  prior  to 
encystment.  An  encysted  resting  stage  is  also  found  in  the  life- 

With  the  object  of  introducing  order  into  the  heterogeneous 
assemblage  of  organisms  which  were,  at  the  time  of  writing,  classed 
as  Monadina,  Cienkowski  proposed  (5)  to  restrict  this  name  to  forms 
which  passed  through  a  life  -  history  approximating  to  that  of 

The  group,  as  thus  limited,  was  regarded  by  him  (8)  as  inter- 
mediate between  animals  and  plants,  and  presenting  affinities  in 


several  directions ;  among  others  with  unicellular  algae,  the 
Mycetozoa  and  such  forms  as  Actinophrys.  Of  these  alliances,  that 
with  the  algae  is  the  least  satisfactorily  established  by  Cienkowski, 
but  that  between  the  "  Monadina "  and  the  Mycetozoa  has  been 
generally  accepted  by  de  Bary  and  later  writers. 

Zopf  (24)  considerably  enlarged  the  "Monadina  "  of  Cienkowski, 
and  in  1887  included  them  in  the  Mycetozoa,  distinguishing  the 
forms  here  included,  as  the  Eu-mycetozoa.  This  course  is  open  to 
objection  on  several  grounds.  The  "Monadina"  of  Zopf  appear 
to  be  still  a  very  heterogeneous  collection  of  forms,  and  their 
inclusion  in  the  Mycetozoa  tends  to  obscure  the  well-marked  features 
of  this  group.  Further,  though  the  affinity  of  some  of  the 
Monadina  with  the  Mycetozoa  seems  probable,  others  are  as  closely 
connected  with  the  Heliozoa,  in  which  class  the  majority  of  them 
are,  in  fact,  included  by  Biitschli  (4).1 

Hence  the  limits  of  the  Mycetozoa,  as  here  understood,  are  the 
same  as  those  drawn  by  de  Bary.  They  include  (1)  the  Sorophora 
of  Zopf  (the  Acrasiae  of  Van  Tieghem) ;  (2)  the  remainder,  and 
great  majority  of  the  species,  for  which  de  Bary  retained  the  old 
name  of  Myxomycetes.  The  only  objection  to  retaining  this  name 
is  that  it  is  generally  used  as  synonymous  with  Mycetozoa.  The 
term  Eu-mycetozoa  would  have  been  preferable,  but  it  is  used  by 
Zopf  to  include  the  Sorophora.  Delage  and  Herouard  have  applied 
the  name  Euplasmodida  to  the  higher  group,  a  course  which  avoids 
all  confusion,  and  emphasises  one  of  the  chief  characters  which  dis- 
tinguishes it  from  the  Sorophora. 

In  a  more  recent  work  (25)  Zopf  has  included  the  Labyrinth uleae  as 
a  sub-order  of  the  Sorophora.  He  has  shown  that  the  singular  network 
described  by  Cienkowski  in  Labyrinthula,  by  which  the  individuals  are 
united,  is  pseudopodial  in  nature,  and  regards  the  whole  colony  as  forming 
a  body  of  the  nature  of  a  plasmodiuni,  to  which  he  applies  the  name 
thread-plasmodium.  There  appears  to  be  no  evidence,  however,  that  the 
term  plasmodiuni  is  any  more  applicable  to  the  colony  of  Labyrinthula 
than  it  is  to  those,  e.y.,  of  Mikrogromia,  or  the  colonial  Radiolaria.  The 
actively  parasitic  habit,  the  entirely  aquatic  life,  the  defined  shape  of  the 
members  of  the  colony,  and  the  absence  of  any  proof  that  it  is  formed 
by  fusion  of  individuals,  keep  Labyrinthula  distinct  from  forms  hitherto 
included  in  the  Sorophora.  Penard  (20a)  has  recently  extended  our  know- 
ledge of  Chlamydomyxa,  showing  that  the  "  oat-shaped  corpuscles "  are 
not  nucleated,  and  therefore  not  comparable  with  the  fusiform  bodies  of 
Labyrinthula  ;  and  also  that  the  contents  of  the  cysts  escape  as  flagellate 
zoospores.  Penard  finds  a  great  analogy  between  this  genus  and  the 

1  Whatever  position  is  ultimately  assigned  to  the  "  Monadina "  of  Cienkowski 
and  Zopf,  it  is  desirable  that  this  name  for  them  should  fall  into  disuse,  for  it  is  now 
applied  in  zoological  works  to  the  simpler  members  of  the  Flagellata,  in  which  the 
flagellate  and  not  the  amoeboid  stage  is  predominant  in  the  life-history. 


Euplasmodida,  a  view  which  is  by  no  means  shared  by  the  writer  of  this 
article.  The  presence  of  chlorophyll  bodies  and  the  stiff  little-branched 
character  of  the  pseudopodia  are  altogether  foreign  to  the  present  group, 
and  here  again  the  plasmodial  nature  of  Ghlamydomyxa  is  far  from  being 
established.  Both  these  genera  are  in  the  present  treatise  dealt  with 
separately  (pp.  274,  280). 

In  addition  to  the  remarkable  phenomena  presented  by  the 
plasmodium  of  the  Euplasmodida,  the  characteristic  and  unique 
feature  of  the  Mycetozoa,  as  a  group,  is  that  belonging,  as 
the  earlier  stages  of  their  life-history  show  them  to  do,  to  the 
animal  stock,  and  developing  their  sporophores  and  sporangia  in 
air,  these  structures  have  been  differentiated  into  a  series  of 
forms  analogous  with  the  sporophores  met  Avith  among  different 
orders  of  fungi.  So  close  is  the  resemblance  in  many  cases,  that 
sporangial  forms  of  each  of  the  three  main  divisions  have  been 
classified  among  the  several  orders  of  fungi :  Dictyostelium 
(Sorophora)  among  the  Mucorinae ;  Cemtiimyxa  (Exosporeae)  with 
the  Basidiomycetes  Polyporus  and  Hydnum ;  and  various  members 
of  the  Endosporeae  with  the  Gasteromycetes. 


(a)  The  Swarm-Cell  or  Zoospore. 

The  spores  of  the  Mycetozoa  are  produced  not  in  water,  as  are 
those  of  the  Monadina  (except  Bursulla),  but  in  air,  and  they  are 
able  to  retain  their  vitality  in  the  dry  state  for  as  many  as  four 
years,  undergoing  no  apparent  change  except  a  collapse  of  the 

spore  owing  to  the  shrinking  of  the 
contents  on  drying.  When  carried 
into  water,  they  rapidly  swell  and 
cv  resume  their  original  form,  which  is, 
in  nearly  all  species,  spherical.  As 
they  lie  in  water  one  or  more  contrac- 
tile vacuoles  make  their  appearance  in 
the  protoplasmic  contents,  and  after 
a  period  varying  from  a  few  hours 
FIO.  i.  to  a  day  or  two,  the  spore  wall  is  rup- 

The  hatching  of  a  spore  of  Fuligo  septica.    turecl,  and  the  Contents  slip  OUt  and 
x  1100.      a,    spore;    6   and  c,    contents    ..      .         .        .  .     , 

emerging  and  undergoing  amoeboid  move-    116  tree  in  the  Water a  maSS  OI  Clear 

^ore\tege^ff;\!v, 'Contractile  vacuoie.00"  protoplasm,  containing  the   nucleus 

and  contractile  vacuoles  (Fig.  1). 

The  first  movements  in  the  free  state  are  amoeboid,  but  an 
elongated  shape  is  soon  assumed ;  and  a  flagellum,  protruded  ten- 
tatively at  first,  becomes  established  at  one  end.  The  organism 


which  thus  enters  the  swarm -cell  or  zoospore  stage  swims  free 
in  the  water  with  a  peculiar  dancing  movement  produced  by  the 
lashing  of  the  flagellum.  In  this  movement  it  rotates  about  its  own 
axis,  and  also  moves  as  though  over  the  surface  of  a  cone,  the  apex  of 
which  is  situated  at  the  posterior  end  of  the  zoospore  (de  Bary). 
It  is  of  an  elongated  pyriform  shape,  the  narrow  ("  anterior  ")  end 
being  continued  into  the  flagellum,  which  is  about  half  to  two- 
thirds  the  length  of  the  body.  The  thicker  ("  posterior  ")  end  may 
be  evenly  rounded,  and  is  then  curled  somewhat  to  the  side,  but 
is  often  extended  in  short  pointed  pseudopodia  (Fig.  2,  «).  The 
protoplasm  of  the  anterior  part  is  hyaline,  and  a  layer  of  hyaline 
protoplasm  invests  the  rest  of  the  body,  the  interior  of  which  is 
granular.  The  nucleus,  with  its  contained  nucleolus,  lies  in  front, 
At  the  base  of  the  flagellum,  and  the  contractile  vacuole  at  the 
posterior  end.  Non-contractile  vacuoles  (some  of  which  at  least 
may  be  food- vacuoles)  are  also  present  in  the  granular  protoplasm. 
The  particles  of  the  latter  exhibit  a  change  of  position  within  the 
body,  which  in  the  large  swarm-cells  of  Amaurocliaete  atra  recalls  the 
streaming  movement  characteristic  of  the  plasmodia  of  the  later  stage. 

Instead  of  swimming  free,  the  swarm -cells  may  temporarily 
assume  an  attached  creeping  mode  of  progression,  in  which  the 
body  is  elongated,  and  the  flagellum,  ex- 
tended in  front,  turns  from  side  to  side 
with  movements  which  appear  to  be  ex- 
ploratory in  purpose.  Sometimes  the  body 
is  contracted  and  sends  out  pseudopodia 
from  all  parts  of  the  periphery  (Fig.  4,  c). 

Bacteria  abound  in  the  wet  places  among 
decaying  vegetable  matter,  in  which  the 
spores  hatch.  These  are  captured  by  the 
zoospores  by  means  of  the  pseudopodia  ex- 
tended from  their  posterior  ends  and  drawn 
into  the  body,  where  they  are  digested  in 
vacuoles  (Fig.  2)  (15).  De  Bary,  to  whom 
this  mode  of  obtaining  food  by  the  zoospores 
was  unknown,  states  (8,  p.  452)  that  their 
nourishment  is  exclusively  saprophytic  at 
this  stage. 
it  may  be 
appears  very  probable  that  it  is  both  holozoic  and  saprophytic. 

The  swarm -cells  multiply  by  division.  In  this  process  the 
flagellum  is  withdrawn,  the  contractile  vacuole  disappears,  and  the 
body  assumes  a  rounded  form.  The  nucleus,  passing  to  the  centre, 
divides  by  karyokinesis  (Fig.  3),  and  as  the  daughter  nuclei  resulting 
from  this  division  separate  the  protoplasm  becomes  constricted,  and 
-division  occurs  in  a  plane  transverse  to  the  axis  of  division  of  the 

Zoospore  of  Stcmnnitis  fusca, 
showing  successive  stages  in 
the  ingestion  of  a  bacillus, 
x  800.  In  «,  it  is  captured  by 
one  of  the  pseudopodia  at  the 
hind  end  ;  in  c,  it  is  enclosed 
in  a  digestive  vacnole.  Another 
bacillus  is  contained  in  an 
(After  A. 

It  is  impossible  to  deny   that  Anterior  vacuole. 

.        .          J     .  Lister,  15.) 

in    part    saprophytic,    and    it 


nucleus.  A  contractile  vacuole  has,  meanwhile,  appeared  in  each 
daughter-cell,  at  a  point  remote  from  the  plane  of  division,  and 
each  develops  a  flagellum  after  separation  is  complete  (15).  It  is- 
probable  that  many  generations  of  swarm-cells  produced  in  this 
manner  succeed  one  another  during  this  stage  of  the  life-history. 

When  the  zoospores  are 
treated  by  Heidenhain's  hae- 
matoxylin  method,  or  with 
picrocarmine,  a  reticulum  comes 
into  view  in  the  nucleus,  and 
the  nucleolus  takes  a  dark  stain. 

FIG.  3. 

Three  stages  in  the  division  of 
zoospore  of  Keticvlaria  lycoperdon. 
x  1000.  (After  A.  Lister,  17.) 

FIG.  4. 

Zoospores  of  Badhamia  panicea, 
stained,     x  650. 

The  nucleus  is  sometimes  round  (Fig.  4,  b),  but  more  often  it  is 
pyriform,  being  drawn  out  towards  the  base  of  the  flagellum 
(Fig.  4,  a).  The  protoplasm  intervening  between  the  nucleus  and 
the  flagellum  is  differentiated  from  the  rest,  and  takes  a  darker 
stain.  It  thus  forms  a  more  or  less  bell-shaped  investment  of  the 
former,  the  contour  of  which  is  most  clearly  seen  in  specimens- 
which  have  assumed  an  amoeboid  shape  without  retracting  the 
flagellum  (Fig.  4,  c). 

Plenge  (21)  first  called  attention  to  this  bell-shaped  structure;  and 
Jahn  (11),  who  has  recently  investigated  it  afresh,  considers  that  it  is- 
part  of  the  spindle  formed  in  nuclear  division  when  the  zoospore  divided^ 
and  remaining  in  connection  with  the  daughter  nucleus.  Jahn's  figures 
illustrating  this  point  are  very  clear,  but  he  does  not  explain  how  the 
structure  is  formed  in  the  zoospore  prior  to  its  first  division. 

In  this  and  also  in  the  succeeding  stage  a  resting  phase  may 
intervene  between  periods  of  activity.  In  it  the  flagellum  and 
pseudopodia  are  withdrawn,  and  the  protoplasmic  body  rounding 
itself  into  a  sphere  secretes  a  hyaline  cyst-wall.  These  cysts  are 
known  as  microcysts.  The  formation  of  microcysts  may  be  readily 
induced  by  allowing  a  cultivation  of  swarm-cells  to  dry  up,  but 
dryness  is  not  a  necessary  condition  for  their  production,  for  they 
are  formed  in  water,  and  some  are  present  in  almost  every  cultivation 
of  swarm-cells. 

(b)  The  Amoebula. 

After  remaining  for  a  period  of  uncertain  duration  in  the  stage 
of  their  life-history  in  which  the  dominant  form  is  that  of  the  free' 



swimming  flagellate  zoospore,  the  flagellum  is  permanently  with- 
drawn and  the  organism  passes  into  the  amoeboid  stage,  which,  as  we 
have  seen,  may  be  temporarily  assumed  daring  the  flagellate  period. 
They  now  creep  about,  adherent  to  other  objects,  emitting  blunt 
pseudopodia,  and  in  this  as  in  the  preceding  stage  they  may  pass 
into  the  condition  of  microcysts. 

Each  individual  in  the  amoeboid  phase  of  the  life-history  is  the 
lineal  descendant,  through  the  successive  divisions  of  the  flagellulate 
phase,  of  a  particular  spore  ;  but  from 
the  amoeboid  phase  onward  the  in- 
dividuality is  lost.  This  results  from 
the  remarkable  process,  first  seen  by 
Cienkowsld  (7),  of  fusion  of  the 
amoebulae  to  form  plasmodia.  The 
amoebulae  present  in  a  particular  area 
draw  together  into  groups,  becoming 
endowed,  apparently,  with  the  power 
of  mutual  attraction,  and  the  groups, 
once  formed,  act  as  centres  to  which 
neighbouring  amoebulae,  scattered 
through  the  water,  converge.  After 
coming  in  contact  with  one  another 
they  remain  at  first  visibly  distinct, 
but  after  a  short  time  a  complete 

fusion  of  the  protoplasm  occurs.  In  this  manner,  the  amoebulae 
from  all  sides  falling  in  and  fusing  in  the  common  mass,  the 
plasmodia  are  produced. 

(c)  The  Plasmodium. 

The  name  plasmodium  was  first  applied  by  Cienkowski  in  1862 
(6,  p.  326)  to  the  large  expansions  of  protoplasm  which  form  the 
dominant  phase  of  the  life-history  of  the  Euplasmodida.  On  his 
subsequent  discovery  (7),  in  1863,  of  their  mode  of  origin  by  the 
fusion  of  amoeboid  swarm-cells,  Cienkowski  stated  (p.  421)  that  such 
a  mode  of  origin  must  be  included  in  the  definition  of  a  plasmodium. 

The  question  arises  whether,  in  this  fusion  of  amoebulae  to  form 
the  plasmodia,  we  have  a  phenomenon  comparable  with  the  conjuga- 
tion of  the  gametes  of  other  forms,  a  view  to  which  the  mutual 
attractiveness  with  which  the  amoebulae  become  endowed  appears 
to  offer  some  support.  If  the  analogy  were  complete,  we  should 
expect  that  a  fusion  of  nuclei  would  occur  as  well  as  a  fusion  of  the 
protoplasm  of  the  amoebulae.  But  the  evidence  which  we  have  at 
present  as  to  the  behaviour  of  the  nuclei  lends  no  support  to  this 
view.  As  many  as  eight  amoebulae  have  been  watched  successively 
fusing  into  a  common  mass,  and  their  eight  nuclei  have  been  seen, 
distinct,  in  the  young  plasmodium  thus  formed  (18,  p.  5).  When 

Fio.  5. 

Amoebulae  of  Dulymium  di/ormc 
uniting  to  form  a  plasmodium.  a, 
separate  amoebulae  ;  m,  microcysts ; 
pi,  young  plasmodium  with  ingested 
bodies,  x  about  320.  (After  A.  Lister, 



the  number  of  fused  amoebulae  increases,  direct  observation  of  the 
behaviour  of  the  nuclei  is,  owing  to  their  small  size  and  the  bulk 
and  movements  of  the  protoplasm,  increasingly  difficult,  and  soon 
becomes  impossible. 

Before  describing  the  plasmodia  in  detail,  it  may  be  briefly 
stated  that  they  are  masses  of  naked  protoplasm  of  indefinite  size, 
containing  numerous  small  nuclei.  As  de  Bary  discovered,  they 
are  capable,  under  certain  conditions,  of  passing  into  a  passive 
condition  known  as  the  Sclerotium,  in  which  the  protoplasm  is 
aggregated  in  cysts  (Fig.  8),  which  together  form  a  mass  of  horn- 
like consistency.  On  the  return  of  favourable  conditions  the 
plasmodium  resumes  the  active  condition. 

The  mode  of  life  of  the  plasmodium  differs  in  different  species, 

FIG.  6. 
Part  of  a  plasmodium  of  Bailhamia  ittriculans  expanded  over  a  slide,     x  S. 

some  (as  in  most  of  the  Trichiaceae  and  Arcyriaceae)  penetrating 
the  interstices  of  dead  wood,  others  (as  of  most  species  of  Craterium 
and  Didymium)  living  among  heaps  of  decaying  leaves,  while  one 
species,  Badlmmia  utricularis,  feeds  on  the  surface  of  living  fungi 
which  grow  from  the  bark  of  dead  trees. 

The  plasmodium  expands  over  surrounding  objects  and  moves 
about,  taking  in  nourishment.  When  exposed,  it  is  seen  by  the 
naked  eye  to  be  traversed  by  systems  of  vessel-like  thickenings,  the 
main  trunks  of  which  divide  and  subdivide  as  they  approach  the 
periphery,  and  are  in  free  communication  by  the  anastomosis  of 
their  branches  (Fig.  6). 

The  border  of  the  plasmodium  in  the  direction  towards  which 
it  is  moving  generally  consists  of  a  continuous  film  of  protoplasm, 
traversed  by  smaller  branches  of  the  system,  but  in  the  other  parts 
the  film  is  generally  not  continuous,  being  interrupted  in  the  inter- 


spaces  between  the  thickenings.  Hence  in  these  regions  the  plas- 
modium  consists  of  a  reticulum  of  anastomosing  branches,  extended 
over  the  substratum.  The  arrangement  of  the  branches  closely 
resembles  that  of  the  vessels  traversing  the  mesentery  of  a  mammal, 
and,  before  their  relation  to  the  spore-bearing  stage  of  the  life- 
history  was  known,  the  name  Mesenterica  was,  in  fact,  given  to 
plasmodia  of  certain  forms,  under  the  supposition  that  they  repre- 
sented a  new  genus  of  fungi. 

The  form  and  degree  of  concentration  of  the  plasmodium 
vary  widely  according  to  circumstances.  Sometimes  it  is 
aggregated  in  a  thick  layer  on  the  surface,  as  after  emerging  from 
the  interstices  of  a  mass  of  rotten  wood  or  tan,  at  other  times  it 
is  widely  expanded  in  a  thin  layer  of  exquisite  delicacy.  Fries 
relates  hoAv  the  plasmodium  of  Diachaea  elegans  which  he  had 
laid  in  his  hat,  while  collecting,  spread  within  an  hour  over  a 
great  part  of  the  latter  in  an  elegant  white  network. 

By  suitable  manipulation  the  plasmodia  may  readily  be  induced 
to  spread  over  glass  cover-slips,  and  may  thus  be  examined  micro- 
scopically.1 When  thus  seen  the  vessel-like  thickenings  are  found 
to  be,  in  fact,  streams  of  moving  protoplasm.  The  flow  may  be 
traced  from  the  larger  branches  through  the  smaller  into  the 
advancing  border  of  the  plasmodium,  which  becomes  swollen  and 
more  opaque  as  the  streams  pass  into  it.  After  a  short  time  the 
current  is  seen  to  slacken,  then  to  stop,  and  shortly  to  begin  again 
in  the  reverse  direction,  the  margin  becoming  thinner  and  more 
transparent  as  the  protoplasm  leaves  it.  In  a  short  time  the  flow 
is  again  reversed,  and  again  directed  to  the  advancing  border. 
Thus  a  rhythmic  flow,  towards  the  margin  and  away  from  it,  is 
kept  up  through  the  plasmodium — the  period  in  each  case  being, 
in  healthy  conditions,  about  a  minute  and  a  half  to  two  minutes, 
though  its  duration  is  always  longer  in  the  direction  in  which  the 
plasmodium  is  moving  than  in  the  other. 

The  plasmodium  is  invested  by  a  thin  layer  of  homogeneous 
hyaline  and  colourless  protoplasm.  Within  this  the  protoplasm  is 
highly  granular. 

The  hyaline  layer  is  exceedingly  thin  over  the  greater  part  of 
the  periphery,  but  at  the  advancing  border  it  is  of  considerable 
breadth.  The  advance  over  the  substratum  occurs  chiefly  while 
the  flow  in  the  veins  is  directed  towards  this  border.  Under 
these  circumstances  the  border  becomes  more  and  more  turgid,  and 

1  An  easy  way  of  making  microscopic  preparations  of  living  plasmodia  is  to  lay 
out  a  number  of  cover-slips  on  a  plate,  sprinkle  them  with  rain-water,  and  then  to 
s., Uter  small  fragments  of  sclerotium  over  them.  In  a  moist  atmosphere  the 
encysted  protoplasm  resumes  the  active  stage  in  the  course  of  a  few  hours,  and  the 
small  plasmodia  thus  arising  spread  in  delicate  fan-like  expansions  over  the  glass. 
The  cover-slips  may  then  be  mounted  over  a  hole  in  wet  blotting-paper,  on  a  slide,  or 
in  some  other  manner,  ensuring  the  maintenance  of  a  moist  atmosphere. 


small  rounded  lobes  of  hyaline  substance  are  seen  to  start  forward, 
and  then  to  become  stationary,  as  though  the  surface  tension  had 
momentarily  been  overcome  by  the  pressure  from  within,  and  had 
then  been  rapidly  renewed.  It  is  to  be  observed  that  the  contents 
of  such  a  newly-formed  lobe  are  at  first  not,  as  might  have  been 
expected,  the  granular  protoplasm  which  flows  in  the  "  veins,"  but 
they  are  hyaline,  the  passage  of  the  granules  into  the  interior  of 
the  lobe  occurring  subsequently. 

The  material  in  the   "  veins  "   appears   to  be   of  highly  fluid 
consistency,    the  granules   moving   over   one    another    with    great 

*,^x>:^£-^:^^-:^:!:-''^  ' ''•'•     . ''''", •'. .-:V>dr-:--:-f^ 

FIG.  7. 

o,  part  of  a  stained  plasmpdium  of  5.  utricularis.  n,  nuclei,  x  110  ;  b,  nuclei,  x  500.  Some 
.are  in  process  of  simple  division,  c,  part  of  a  plasmodium  in  which  the  nuclei  are  in  simul- 
taneous division  by  karyokinesis.  <?-/,  other  stages  in  this  mode  of  division,  x  650. 

freedom.  When  a  small  channel  is  watched  it  frequently  occurs 
that  an  ingested  sclerotium  cyst  or  other  large  object  blocks  a 
narrow  part,  and  the  flow  in  the  channel  is  temporarily  checked. 
If  the  object  ultimately  passes  on,  its  passage  is  followed  by  a 
gush  of  the  protoplasm  behind  it,  at  increased  velocity,  the  flow 
gradually  resuming  its  normal  rate.  When  a  vein  traversing  a 
continuous  portion  of  the  plasmodial  film  is  examined  the  flow  is 
seen  to  be  rapid  at  the  centre  and  slower  at  the  sides. 

The  phenomena  presented  by  the  circulation  in  the  veins  suggest 
the  view  that  their  contents  are  passively  propelled,  as  the  result  of 
the  contraction  of  the  more  external  part  of  the  plasmodial  substance. 


De  Baiy  concluded  (2,  pp.  43-51)  that  besides  such  a  positive 
vis  a  tergo,  due  to  contraction  of  the  protoplasm  in  the  regions  from 
which  the  flow  occurs,  there  is  evidence  of  a  negative  pressure 
exercised  by  the  plasmodium  in  the  regions  towards  which  the  flow 
is  going,  and  due  to  its  expansion  from  the  previous  state  of 

While  the  conclusion  appears  probable  that  the  streaming 
movement  is  due,  in  part  at  any  rate,  to  the  contraction  of  the 
outer  portions  of  the  protoplasm,  we  may  bear  in  mind  that  such 
an  explanation  appears  inapplicable  to  other  phenomena,  which  we 
should  expect  to  belong  to  the  same  category,  such  as  those 
exhibited  by  the  pseudopodia  of  the  Foraminifera,  in  which 
streams  of  granules  course  along  a  filament  of  extreme  tenuity  in 
opposite  directions. 

When  a  piece  of  sclerotium  resumes  activity  on  being  wetted, 
it  sends  out  a  fan- like  expansion  over  the  substratum,  and  the 
rhythmic  flow  is  seen  to  be  alternately  away  from  the  central  mass 
and  back  to  it ;  but  as  the  fans  extend  farther  over  the  substratum, 
the  flow  in  the  several  parts  of  the  plasmodium  becomes  less  and 
less  co-ordinated,  in  proportion  as  they  separate  from  one  another. 
The  several  parts  separate  into  distinct  plasmodia,  and  distinct 
plasmodia  fuse  with  complete  freedom. 

Reaction  of  Plasmodia  to  External  Conditions. — Experiments  testing 
the  reaction  of  plasmodia  to  variations  in  external  conditions  have 
led  to  some  positive  results,  an  interesting  account  of  which  is 
given  by  Stahl  (22). 

During  the  vegetative  period  of  their  existence  plasmodia  move 
from  the  drier  to  the  moister  parts  of  their  substratum,  though  at 
the  approach  of  the  spore-producing  stage  the  movement  is  in  the 
opposite  direction,  the  organism  seeking  the  driest  part  of  its  en- 
vironment whereon  to  undergo  its  change  into  spores.  Connected 
apparently  with  the  favourable  influence  of  a  moist  atmosphere  is 
the  phenomenon,  familiar  to  tanners,  of  the  "  flowering  of  the  tan- 
heaps  "  at  the  approach  of  wet  weather.  This  consists  of  the 
emergence  at  the  surface  of  the  bright  yello.w  plasmodia  of  Fuligo 
septica,  commonly  known  as  Flowers  of  Tan,  which  abound  in  the 
heaps,  and,  except  under  such  conditions  (and  at  the  approach  of 
sporulation),  inhabit  the  deeper  parts  of  the  heap. 

When  water  is  allowed  to  flow  through  the  substratum, 
plasmodia  move  in  a  direction  opposite  to  the  current,  a  tendency 
which  may  be  utilised  for  the  purpose  of  isolating  them  for 
experimental  purposes.  By  arranging  strips  of  filter  paper,  through 
which  water  is  flowing,  so  that  their  lower  ends  rest  on  the  mass 
containing  the  plasmodia,  the  latter  will  crawl  up  the  filter  paper, 
and  may  thence  be  transferred,  in  the  same  manner,  to  glass  slides. 


The  presence  of  substances  suitable  for  food  exercises  a  strong 
attraction  on  plasmodia.  When  the  spreading  border  touches 
such  a  substance  the  streaming  movement  is  at  once  quickened  in 
this  direction,  and  the  outlying  lobes  being  drawn  in,  the  whole 
plasmodium  is  rapidly  concentrated  on  the  nutrient  material  (14). 

The  contrary  effect  is  seen  when  harmful  substances  are  brought 
into  their  neighbourhood. 

The  plasmodia  of  many  species  are  said  to  shun  the  light,  but 
this  is  not  the  case  with  all ;  that  of  Badhamia  utricularis,  for 
example,  will,  if  a  moist  atmosphere  be  maintained,  continue  to 
spread  over  the  pilei  of  the  fungi  on  which  it  feeds,  though  these 
may  be  exposed  to  full  sunlight. 

Nuclei. — The  plasmodia  are  multinucleate  from  their  origin; 
but  from  the  fact  that  a  minute  plasmodium  a  few  millimetres  in 
diameter  will  grow,  when  supplied  with  food,  till  it  is  many  inches 
in  diameter,  and  that  the  nuclei  are  then  as  numerous,  in  a  small 
sample,  as  they  were  before  the  growth  had  occurred,  it  is  clear 
that  the  nuclei  increase  in  number  pari  passu  with  the  growth  of 
the  protoplasm.  There  is  reason  to  believe  that  this  increase  occurs 
in  two  ways,  (a)  A  simultaneous  division  of  the  nuclei  by  karyo- 
kinesis  has  been  found  to  be  in  progress  when  plasmodia  (of  Badhamia 
utricularis,  Fig.  7,  c-f)  are  stained  (17,  p.  541) — a  process  comparable 
apparently  with  the  simultaneous  division  of  nuclei  which  occurs  in 
the  vegetative  stage  of  Actinosphaerium.  (b)  Multiplication  by  simple 
division  is  not  easy  to  establish,  where,  as  in  this  case,  prolonged 
observation  of  the  nuclei  in  the  living  state  is  rendered  difficult  by 
the  movement  of  the  plasmodia,  but  the  following  observation  appears 
to  show  that  it  is  of  frequent  occurrence  in  their  groAvth  : — 

A  plasmodium  of  Badhamia  utricularis,  spreading  and  feeding  on 
the  pilei  of  the  fungus  Auriculuria,  increased  in  size  about  fourfold 
in  fourteen  hours;  and  during  this  time  a  small  portion  of  it  was 
removed,  smeared  on  a  cover-slip,  and  fixed  every  quarter  of  an  hour. 
On  staining  the  56  samples  so  obtained,  the  nuclei  were  found  to  be 
approximately  equally  abundant  in  all,  and  presented  considerable 
differences  in  size,  but  in  no  case  was  there  any  indication  of  karyo- 
kinetic  division.  Now  in  the  karyokinetic  division  of  nuclei  which 
occurs  prior  to  spore-formation  (see  p.  52)  the  process  lasts  from  one 
to  one  and  a  half  hours.  Assuming  the  same  duration  for  the 
karyokinetic  division  of  the  nuclei  in  the  growing  plasmodium,  and 
bearing  in  mind  that  the  division  in  this  manner,  when  observed, 
was  simultaneous,  we  must  conclude  that  it  had  not  occurred  in 
the  fourteen  hours  during  which  the  observations  were  made ;  yet 
from  these  observations  it  appears  that  in  this  period  the  number 
of  the  nuclei  had  increased  about  fourfold  (18,  p.  9).  As  a  fact, 
the  appearance  of  the  nuclei  in  various  phases  of  constriction  is  of 
common  occurrence  when  stained  plasmodia  are  examined  with  a 


high  power  (Fig.  7,  b),  but  the  appearance  is  so  similar  to  that  of 
overlapping  nuclei,  that  without  the  confirmation  afforded  by  the 
experiment  above  described,  the  conclusion,  that  in  addition  to  a 
periodic  (?)  increase  by  mitosis,  the  nuclei  multiply  by  simple 
division,  could  hardly  have  been  accepted  as  secure. 

With  regard  to  the  distribution  of  the  nuclei,  it  is  to  be  observed 
in  stained  preparations,  in  which  the  plasmodium  has  been  suddenly 
killed,  that  they  appear  to  be  as  numerous  in  proportion  to  the  bulk 
of  the  protoplasm  in  the  veins  as  they  are  in  the  film  of  the  plas- 
modium on  either  side  of  them. 

In  size  the  nuclei  vary  from  2 '5  to  5  /x.  In  the  resting  condi- 
tion they  present  a  well-marked  reticulation  and  a  distinct  nucleolus. 

In  mitosis  a  well-marked  spindle  is  formed,  and  the  chromosomes 
are  rounded  and  compact.  In  number  the  latter  appear  to  be 
about  8  or  9,  in  Trichia  (see,  however,  p.  65).  It  may  be  noted 
that  as  in  other  Protozoa  the  nuclear  membrane  is  maintained 
until  after  the  separation  of  the  chromosomes  to  form  the  daughter 

Contractile  Vacuoles  abound  in  the  peripheral  layer  of  the  plas- 
modium, and  may  be  readily  seen  in  the  expansions  between  the 
channels.  They  are  generally  about  7-8  p  in  diameter. 

The  protoplasm  contains  abundant  granules,  of  minute  size, 
the  nature  of  which  has  not  been  ascertained.  In  one  group  of 
Mycetozoa,  the  Calcarineae,  granules  of  carbonate  of  lime  abound 
in  the  plasmodia.  They  are  not  present  in  other  species,  and  their 
relation  to  physiological  processes  is  obscure. 

The  plasmodia  of  many  species  are  white,  but  those  of  others 
are  yellow,  pink,  purple,  or  green,  and  owe  their  colour  to  a  fluid 
pigment  scattered  in  small  drops  through  the  protoplasm.  In  the 
Calcarineae,  the  fluid  pigment  invests  the  granules  of  lime. 

The  Food  of  Plasmodia. — The  plastnodia  of  the  great  majority  of 
the  Mycetozoa  feed  on  the  decaying  vegetable  matter  among  which 
they  live.  Their  mode  of  nutrition  must  be  regarded  as  both 
saprophytic  and  holozoic,  for  they  are  able  to  absorb  nutrient 
matters  in  solution  (cf.  Stahl,  22)  as  well  as  to  engulf  their  food. 
Those  living  among  leaves  and  under  bark  are  found  charged  with 
particles  which  have  been  ingested,  and  the  undigested  portions 
are  found  strewn  along  the  track  they  have  traversed.  Badhamia 
utricularis  is  exceptional  in  feeding  on  living  fungi  (Stereum,  Auri- 
cularia,  etc.),  though  it  will  also  live  and  thrive  on  the  same  fungi 
after  they  have  become  dried,  if  they  are  wetted  again  with  water. 

Experiments  have  shown  that  proteids  (coagulated  albumen, 
sclerotium  cysts),  taken  in  by  plasmodia,  are  digested  in  vacuoles 
into  which  an  acid  is  secreted  by  the  surrounding  protoplasm  (see 
the  experiments  by  Miss  Greenwood  and  Miss  Saunders,  10), 


although  the  reaction  of  the  plasmodium  as  a  whole  is  alkaline 
(Metschnikoff,  19).  Pepsine,  the  presence  of  which  in  plasmodia  of 
Fuligo  was  shown  by  Krukenberg  (12),  is  doubtless  the  agent  by 
which,  acting  in  this  acid  medium,  the  digestion  is  brought  about. 

Raw  starch  grains  which  had  been  ingested  were  found  to  pass 
unaltered  through  the  plasmodium  of  Badhamia  utricularis,  though 
grains  which  had  been  previously  swollen  in  warm  water  were 
digested  (14). 

The  plasmodium  of  this  species  at  any  rate  has  the  power  of 
dissolving  cellulose.  This  is  evident  from  the  nature  of  its  food, 
and  has  also  been  directly  observed  (14)  when  a  plasmodium  was 
seen  to  extend  over  the  hyphae  of  a  mould.  The  cellular  walls  of 
the  hyphae  were  dissolved  "  like  sugar  in  hot  water  "  as  soon  as  the 
hyaline  border  of  the  plasmodium  reached  them. 

The  Sclerotium  Condition. — As  in  the  earlier  phases  of  the  life- 
history,  a  passive  condition  may,  as  we  have  seen,  be  assumed  in 
the  plasmodium  stage,  the  protoplasmic  mass  breaking  up  into 
cysts  and  assuming  as  a  whole  a  firm  consistence.  To  this  con- 
dition de  Bary  gave  the  name  Sclerotium.  As  it  supervenes, 
the  streaming  movements  gradually  cease,  foreign  bodies  are 
extruded,  and  the  plasmodium  becomes  separated  into  distinct 

masses,  each  of  which  contains  10-20 
nuclei,  and  secretes  a  membranous  cyst- 

The  assumption  of  the  sclerotium 
condition  is  readily  induced  by  allowing 
plasmodia  to  dry,  and  when  so  treated 
they  assume  a  firmer  and  firmer  con- 
sistency, until  the  masses  of  cysts  attain 
a  hard  and  horn-like  condition,  in  which 

Part  of  a  section  of  the  plas-       .  • 

medium  of  Sadkamia  utricularis  vitality  may  be  preserved  for  as  many 

when  passing  into  the  sclerotium  ,-,  c,  •,        ,  • 

condition,    x  310.   «,  a  nucleus,      as   three  years.     Sclerotium  cysts  may, 

however,  be    formed  in  water,  but  the 

conditions  under  which  this  occurs  are  obscure.  When  the  dry 
sclerotia  are  placed  in  water  the  protoplasmic  masses  absorb  or 
break  through  the  cyst-walls,  fuse  together,  and  the  active  plas- 
modial  condition  is  resumed.  The  revival  occurs  in  a  few  hours. 

It  is  to  be  noted  that  the  unit  represented  by  the  sclerotial 
cyst  is  different  from  the  microcyst  of  the  preceding  stages,  which 
was  uninucleate,  and  also  from  the  sporangium  of  the  succeeding 
stage,  which  is  much  larger,  and  contains  a  much  greater  number  of 

(d)  The  Formation  of  Sporangia. 

The  conditions  under  which  plasmodia  pass  into  the  succeed- 
ing phase,  that  of  spore-production,  are  in  part  obscure,  but  one 


element  in  this  result  is  the  absence  of  further  nourishment.  In  a 
cultivation  of  Badhamiu  utricularis,  after  the  plasmodium  has  been 
supplied  with  abundant  food,  arid  has  increased  largely  in  bulk,  the 
formation  of  sporangia  may  generally  be  induced  by  withholding 
the  supply  of  fungus,  which  is  the  food  material  of  this  species. 
If  while  food  is  withheld  a  suitable  substratum,  such  as  clean 
sticks,  is  supplied,  the  plasmodium  will  generally  creep  on  the 
sticks  and  there  form  into  sporangia. 

The  mode  of  formation  of  the  sporangia  in  this  species  may 
be  described  as  characteristic  of  the  majority  of  Mycetozoa,  the 
principal  departures  from  the  type  being  subsequently  noticed. 

As  seen  by  the  naked  eye,  the  plasmodium  previously  extended 
in  a  diffused  network  over  the  substratum  is  seen  to  become 
aggregated  in  lobed  masses  0*5  to  1  mm.  in  diameter,  which  in  this 
species  are  grouped  closely  together,  and  vary  in  number  from  a 
few  to  many  thousands,  in  proportion  to  the  size  of  the  plasmodium. 
These  are  at  first  connected  by  the  veins  of  the  plasmodium,  and 
may  be  seen  to  expand  and  contract  in  accordance  with  the 
direction  of  the  streaming  movement,  which  is  still  maintained. 
Gradually,  however,  the  veins  connecting  them  diminish,  and  soon 
the  whole  protoplasm  is  completely  segregated  into  distinct  lobes, 
or  young  sporangia. 

While  the  formation  of  the  sporangia  is  in  progress,  all  re- 
maining foreign  bodies  which  have  been 
ingested  with  food  in  the  plasmodial 
stage  are  expelled,  and  a  secretion  takes 
place  of  a  structureless,  transparent  sub- 
stance which  serves  for  the  support 
and  enclosure  of  the  spores.  At  the 
surface  of  each  of  the  lobed  masses, 
constituting  the  young  sporangia,  is 
thus  formed  a  sporangium  wall,  which 
in  the  mature  state  is  a  thin  wrinkled 
membrane,  completely  investing  it.  At 
the  constricted  base  of  the  sporangium 
this  is  continued  to  the  substratum  as  a 
slender  stalk  of  varying  length  (Fig.  9). 

While  the  sporangium  wall  is 
secreted  on  the  surface  of  the  spor- 
angium, a  similar  process  occurs  along 

certain    tracts    throughout    the    interior,       a,  a  group  of  sporangia  of  Badhamia 

aivino-  risp  /in  tnia  cnpr>if>cA  fn  an  -mocrn  utricularis.  X  12.  b,  a  cluster  of 
giving  rise  (in  tniS  Species;  to  an  anaSCO-  spores ;  c>  a  single  spore  ;d,  part  of  the 

mosing  network  of  flat  bands  with  capillitium  containing  lime  granules. 
,  °  .  .  b  and  d  x  170.  (After  A.  Lister,  18.) 

broad,  thin  expansions  at  the  points  ot 

junction  (d).      From  a  superficial  resemblance   to  a  structure  in 

•Gasteromycetous  Fungi,  this  network  traversing  the  interior  of 


the  sporangium  is  known  as  the  capillitium.  At  the  periphery  it  is 
continuous  with  the  sporangium  wall. 

The  lime  granules,  which  existed  free  in  the  plasmodium,  pass 
out  of  the  protoplasm  simultaneously  with  this  secretion.  Some 
are  sparsely  scattered  through  the  sporangium  wall,  but  the 
majority  are  closely  packed  in  the  strands  of  the  capillitium,  which 
are  white  and  brittle  in  consequence  (Figs.  9,  d,  and  10). 

Until  the  secretion  of  sporangium  wall  and  capillitium  is 
complete  the  protoplasm  remains  a  homogeneous  mass,  with 
multitudes  of  nuclei  scattered  through  it.  Their  completion  is 
followed  by  a  division  of  the  nuclei  by  karyokinesis,  which  occurs 

Fio.  10. 

20.    To  the  left  are  three  sporangia,  the  walls  of  which 
H  naniiijtium.    Three  to  the  right  are  unopened  ;  above 
of  the  capillitium. 

simultaneously  throughout  the  sporangium  and  occupies  from  one 
to  one  and  a  half  hours  (Fig.  II).1  While  this  is  in  progress  the 
protoplasm  breaks  up  into  rounded  masses  which  contain  some  6-10 
nuclei,  but  they  subsequently  divide  into  masses,  each  containing 
one  of  the  dividing  nuclei ;  and  as  the  nuclear  division  is  completed 
and  the  daughter  nuclei  draw  apart,  a  further  division  of  the 
protoplasm  occurs,  and  each  nucleus  then  occupies  a  single  mass 
of  protoplasm  (Fig.  12).  These  masses  are  the  young  spores. 
They  soon  secrete  a  spore-wall  which  is  of  a  violet-brown  colour^ 

1  This  was  first  observed  by  Strasburger  (23)  in  Trichia  fallax.  The  observation 
has  been  repeated  by  my  father  in  two  other  species  of  Trichia,  and  in  representatives 
of  the  genera  C'omatricha,  Physarum,  and  Badhamia  (17),  and,  since  that  paper  was- 
published,  in  Reticularia  and  Arcyria. 



and  covered  with  minute  spines  or  tubercles.     The  spores  are  ap- 
proximately spherical,  and  9  to  12  yu.  in  diameter.    In  several  species 

the  spore -wall  has  been   found  to 
give  the  reaction  of  cellulose. 

Fio.  11. 

Tart  of  a  section  through  a  young 
sporangium  of  Trichia  varia,  showing 
the  division  of  the  nuclei  prior  to 
spore  -  formation.  x  650.  c,  capil- 
litium  thread ;  n,  a  nucleus.  In 
several  cases  the  axis  of  the  dividing 
nucleus  is  directed  towards  us,  and 
the  karyokinetic  figure  is  therefore 
not  displayed. 

Part  of  a  section  through  a  spor- 
angium of  Trichia  raria  after  the 
spores  are  formed.  Capillitium 
threads  are  seen  in  longitudinal  and 
transverse  section,  x  650. 

The  ripe  sporangium  thus  consists  of  a  mass  of  spores, 
enveloped  by  the  sporangium  wall  and  traversed  by  a  supporting 
reticulate  capillitium,  which,  like  the  wall,  has  a  dry  membranous 
character,  though  charged  throughout  with  white  granules  of  lime. 
As  ripening  proceeds  the  sporangium  wall  becomes  more  and  more 
friable,  until  it  breaks  and  the  spores  are  spread  abroad  on  the 
lightest  currents  of  air. 

Considerable  variations  of  structure  are  presented  by  the 
sporangia  of  the  Mycetozoa.  The  stalk  may  be  absent  altogether, 
the  sporangia  being  sessile  on  the  substratum  (Fig.  13,  e).  When 
present  it  is  usually  solid,  but  may  be  hollow,  and  sometimes,  as  in 
Trichia  fallax,  may  contain  cellular  elements,  which  appear  to  be 
aborted  spores. 

In  many  species  the  stalk  is  continued  in  the  interior  of  the 
sporangium  as  a  structure  known  as  the  columella,  which  may  reach 
to  the  apex  or  terminate  short  of  it.  A  columella  may,  however, 
be  present  in  sessile  sporangia,  as  in  species  of  Chondrioderma 
(Fig.  13,  e}. 

Stalked  sporangia  are,  at  their  first  formation,  sessile,  and  in 
the  majority  of  cases  the  stalk  may  be  regarded  as  the  basal  part 
of  the  sporangium  wall,  which  has  shrunk  and  fallen  in  about  the 
base  of  the  sporangium,  as  the  latter  has  risen  above  the  substratum 
(Figs.  13,  a,  and  15,  a) ;  but  in  the  Stemonitaceae  the  stalk,  with  its 



continuation,  the  columella,  is,  as  de  Bary  showed,  an  axial  structure 
secreted  in  the  interior  of  the  young  sporangium  (Fig.  14,  a-e).  In 
the  formation  of  these  sporangia  the  basal  portion  of  the  stalk  is 
formed  first  and  additions  are  made  to  the  apex  as  the  protoplasm 
climbs  Up  this  axial  support.  In  Stemonitis  fusca  and  splendens  the 
stalked  sporangia  may  attain  a  height  of  20  mm. 

In  addition  to  the  skeletal  or  supporting  structures  of  the  spore- 
bearing  stage  above  mentioned,  another  is  present  in  many  genera — 
the  hypothallus.  This  consists  of  a  network  of  strands  or  a  con- 
tinuous film,  formed  of  the  same  material  as  the  other  supporting 
structures,  extended  over  the  substratum,  and  forming  the  base 
on  which  the  sporangia  are  inserted  (cf.  Fig.  13,  d).  Its  presence 
apparently  depends  on  the  occurrence  of  the  secretion,  in  the  later 

FIG.  13. 

a,  sporangia  of  Physarum  nutans,  Pers.,  x  15.  6,  piece  of  sporangium  wall,  with  groups  of 
lime  granules,  capillitium  threads,  with  lime-knots  (k)  and  spores  of  Physancm,  nutans,  x  210. 
c,  spore  of  same,  x  450.  d,  sporangia  of  Craterium  pedunculatum,  Trent,  each  with  a  discoidal 
hypothallus  at  the  base  of  the  stalk,  x  17.  e,  sporangia  of  Chondriodermu  tcstaceum,  Host., 
showing  the  double  sporangium  wall  (outer  layer  with  lime,  inner  membranous),  and  in  the 
upper  sporangium  the  columella,  x  15.  /,  threads  of  the  capillitium  of  the  same,  x  280.  g, 
group  of  crystals  of  lime  from  the  wall  of  Spumaria  alba,  x  210.  h,  a  crystalline  disc  from 
the  sporangium  wall  of  Lepidoderma  tigrinuam,  Rest.,  x  210.  (After  A.  Lister,  18.) 

stages  of  the  plasmodial  condition,  of  the  substance  which  dries  into 
the  supporting  material — its  reticular  or  continuous  character  corre- 
sponding with  the  state  of  diffusion  of  the  plasmodium  during  its 

The  sporangium  wall  may  consist  of  two  layers  as  in  Chondrioderma 
(Fig.  13,  e),  where  the  outer  is  densely  charged  with  lime  granules, 
and  the  inner  is  membranous  and  free  from  lime.  In  some  species 
of  Craterium  (Fig.  13,  d)  the  upper  portion  of  the  sporangium  wall 
forms  a  lid,  which  readily  falls  away,  exposing  the  contents.  In 
Didydium  (Fig.  14,/)  and  Cribraria  the  wall  of  the  mature  sporangium 
is  represented  wholly  or  in  part  by  an  open  network,  through  the 



meshes  of  which  the  ripe  spores  escape ;  and  in  Comatricha  it  is 
evanescent,  and  disappears  soon  after  the  sporangia  are  ripe. 

The  capillitium  also  presents  great  variation.  In  the  genera  form- 
ing the  Calcarineae  the  lime  may  be  uniformly  distributed  through 
it  (Badhamia,  Figs.  9  and  10)  or  collected  into  lumps  ("lime-knots") 
at  the  points  of  junction  of  the  reticulum  (Physarum,  Fig.  13,  b, 
Fuligo,  Craterium).  In  Chondrioderma  (Fig.  13,  e  and  /),  Didymium, 
and  others  the  lime  is  only  laid  down  in  or  on  the  sporangium  wall 
and  the  capillitium  is  free  from  it.  The  strands  of  the  capillitium 
are  generally,  though  not  invariably,  continuous  at  the  periphery 
with  the  sporangium  wall,  and  internally  with  the  columella,  if  this 
structure  is  present. 

FIG.  14. 

a,  four  sporangia  of  Stcmonitis  splendens,  Rost.;  that  to  the  right  is  represented  free  from 
spores  and  shows  the  columella  extending  nearly  to  the  top  ;  x  2.  b,  part  of  an  empty 
sporangium  of  S.  splendens,  showing  the  columella  (c)  and  a  branch  springing  from  it  and 
dividing  to  form  the  surface  network  of  the  capillitium.  To  the  right  a  group  of  spores,  d,  e, 
stages  in  the  development  of  the  sporangia  of  Stemonitis  ferruginea,  Ehrenb.,  showing  the 
development  of  the  columella  in  the  axis  of  the  young  sporangium.  The  space  between  the 
columella  and  the  protoplasm  is  artificial.  /,  empty  sporangium  of  Dictydium  umbilicatum, 
Schrad.,  x  30.  (d  and  e  after  de  Bary,  2  ;  the  other  figures  after  A.  Lister,  18.) 

The  capillitium  attains  its  most  elaborate  development  in  the 
Arcyriaceae  and  Trichiaceae  (Fig.  15).  In  the  former  it  consists  of 
an  elastic  network,  attached  or  not  to  the  base  of  the  sporangium, 
but  free  from  its  sides,  and  with  the  strands  beset  with  spines  or 
transverse  thickenings,  resembling  cogs  on  a  wheel  (Fig.  15,  /).  At 
maturity  the  evanescent  film  of  the  sporangium  wall  gives  way  and 
the  capillitium  expands  into  a  long  loose  tangle,  scattering  the  spores. 

In  the  Trichiaceae  the  threads  of  the  capillitium  have  spiral 
thickenings.  In  Hemitrickia  the  threads  are  united  into  a  network, 
as  in  Arcyria,  but  in  Trichia  they  are  usually  unbranched  and  lie 
free  among  the  spores  (Figs.  11,  12,  and  15,  b).  Owing  to  their 
spiral  sculpture  they  twist  and  untwist  with  varying  changes  of 
moisture,  and  thus  subserve  the  distribution  of  the  spores. 

In  a  large  section  of  genera,  the  Anemineae,  a  capillitium  is 


In  the  Physaraceae  the  lime  is  aggregated  in  the  sporangium  in 
the  form  of  granules ;  but  in  the  Didymiaceae,  though,  as  in  other 
Calcarineae,  granular  in  the  plasmodium  stage,  it  assumes,  when 
separating  from  the  maturing  sporangium,  a  crystalline  form,  being 
deposited  on  the  sporangium  wall  either  in  clusters  of  crystals 
(Didymium  and  Spumaria,  Fig.  13,  g)  or  in  discs  with  a  radiating 
arrangement  (Lepidoderma,  Fig.  13,  /t).  It  is  clear  that  in  this 
process  the  lime  must  be  in  a  state  of  solution  as  it  passes  through 
the  sporangium  walls. 

The  spores  vary  in  diameter  from  3-5  yu,  (in  Tubulina  stipitata)  to 
16-20  /x  (in  Licea  pusilla) ;  and  the  size  is  generally  approximately 
uniform  in  each  species.  The  surface  may  be  smooth,  tuberculated, 



FIG.  15. 

a,  sporangia  of  Trichia  varia,  x  15  ;  6,  one  of  the  capillitium  threads ;  c,  spores,  x  160 ;  <?, 
a  spore  of  Hcmitrichia  chrysospora,  x  nearly  600  ;  c,  sporangia  of  Arcyria  incarnata  ;  in  one  the 
sporangium  wall  lias  broken  and  the  capillitium  has  expanded,  in  another  the  empty  base 
alone  remains,  x  16  ;  /  and  g,  capillitium  and  spores  of  A.  punicea,  x  160.  (a,  d,  and  e,  after 
A.  Lister,  18.) 

or  reticulated  (Fig.  15,  d) ;  and  the  sculpture  may  be  absent  from 
one  side  of  a  spore,  a  peculiarity  generally  associated  with  the 
arrangement  of  the  spores  in  clusters. 

Aethalia  and  Plasmodwcarps. — In  several  species  of  Mycetozoa 
the  sporangia,  instead  of  standing  apart,  are  more  or  less  closely 
fused  to  form  large  compound  bodies  known  as  Aethalia,  which 
present  characteristic  features  of  shape  and  structure.  The  identity 
of  the  individual  sporangia  may  remain  obvious  or  be  entirely  lost 
in  the  mature  aethalia,  but  in  the  course  of  their  development  their 
compound  nature  is  usually  evident. 

In  many  cases  (Fuligo,  Fig.  16,  Iteticularia,  Lycogala)  the  proto- 
plasm Avithdraws  from  the  peripheral  portions  of  the  sporangia,  the 
walls  of  which  collapse  in  consequence  and  together  form  a  cortical 
layer,  and  a  similar  withdrawal  of  protoplasm  from  the  basal 



region  often  gives  rise  to  a  spongy  base  to  the  aethalium,  to 
which  the  name  hypothallus  has  been  loosely  applied,  though  the 
structure  is  as  distinct  from  the  true  hypothallus  as  is  any  other 
part  of  the  supporting  substance. 

Many  Mycetozoa  forming  aethalia  are  closely  allied  to  species 
with   discrete   sporangia.      Thus    Fuligo  is  an   aethalioid    form  of 

Fio.  16. 

Aethalium  of  Fuligo  septica.  a,  part  of  a  ripe  aethalium  in  section,  showing  the  cortical 
layer,  x  1.  b,  part  of  a  section  of  the  developing  aethalium,  showing  the  separate  convoluted 
tubular  sporangia_of  which  the  aethalium  is  composed,  x  about  390.  (After  de  Bary,  2.) 

Physarum,  Spumaria  of  Didymium;  and  species  in  which  the 
sporangia  are  usually  distinct  may  assume  an  aethalioid  form,  as  in 
the  "  confluent "  variety  of  Stemonitis  fusca. 

In  some  species  the  plasmodium  does  not  become  rounded  off  into 
distinct  and  symmetrical  spor- 
angia in  the  spore-producing 
stage,  but  retains  a  diffused 
.and  lobate  form.  In  other  re- 
spects maturation  proceeds  as 
in  ordinary  sporangia.  These 
bodies  are  known  as  plas- 
modiocarps (Fig.  17).  Aethalia 
appear  to  be  formed  by  the 
fusion  of  sporangia,  while 
plasmodiocarps  are  sporangia 
incompletely  segregated. 

Plasmodiocarps  are  characteristic  of  some  genera  (Licea),  but 
frequently  occur  together  with  completely -formed  sporangia  in 
the  same  species  of  others. 


The  genus  Ceratiomyxa  (formerly  known  as  Ceratium),  the  single 
representative  of  the  Exosporeae,  differs  from  the  Endosporeae 

Fio.  17. 

The  plasmodiocarp  form  of  Diili/minm  rffusum. 
x  15.     (After  A.  Lister,  18.) 


in  the  relation  of  the   spores  to  the  supporting  structures,   and 

in  the  changes  which  occur 
when  the  spores  are  hatched 
(Fig.  18). 

The  plasmodium  inhabits 
rotten  wood  and  emerges  in 
cushion-like  masses,  which  may 
become  honeycombed  with  de- 
pressions or  separate  into  dis- 
tinct antler-like  branches.  On 
its  emergence  it  assumes  the 
condition  of  an  intimately 
anastomosing  network  of  pro- 
toplasmic strands  distributed 
through  an  abundant  hyaline 
gelatinous  substance,  and  at 
first  exhibiting  the  characteristic 
rhythmic  ebb  and  flow  seen  in 
the  plasmodium  of  the  Endo- 
sporeae.  As  the  definitive 
shape  is  assumed,  the  proto- 
plasm leaves  the  interior  and 
accumulates  at  the  surface  of 
the  mass,  at  first  as  a  close- 
set  reticulum,  and  then  as  a  continuous  layer  investing  the 
gelatinous  substance,  though  with  a  thin  covering  of  the  latter  still 
external  to  it.  The  layer  of  protoplasm  then  separates  into  a- 
mosaic  of  polygonal  cells  (Fig.  18,  b),  each  occupied  by  one  of  the 
nuclei  of  the  plasmodium.  The  cells  are  at  first  in  contact  with 
their  fellows  at  their  margins,  but  they  now  draw  apart,  and  each 
projects  in  the  centre  of  the  area  which  it  occupied,  beyond  the 
contour  of  the  lobe  on  which  it  lies,  though  still  covered  by  the 
thin  hyaline  layer.  As  the  projection  increases  its  base  becomes- 
constricted,  and  finally  the  cell,  or  young  spore,  containing  the 
nucleus  and  all  the  protoplasm  which  occupied  the  polygonal  area, 
is  raised  some  distance  above  the  general  surface,  invested  by 
a  thin  covering,  and  supported  on  a  slender  stalk — both  furnished 
by  the  investing  layer.  Each  spore  now  assumes  an  elliptical 
shape,  secretes  a  firm  colourless  wall,  and  is  ready  to  drop  away.1 

During  the  later  stages  of  this  process  the  gelatinous  material' 
constituting  the  sporophore  dries,  and  by  the  time  the  spores  are 
ripe,  forms  a  shrivelled,  white  mass  of  extreme  tenuity  (Fig.  18,  a). 
According  to  Famintzin  and  Woronin  (9),  who  first  described  the 
details  of  the  life-history  of  Ceratiomyxa,  the  protoplasm  emerges  in 
the  morning  and  the  spores  are  ripe  within  twenty-four  hours. 

1  For  nuclear  changes  during  spore-formation,  cp.  p.  66. 

FIG.  18. 

Ceratiomyxa  mucida,  Schroet.  a,  ripe 
sporophore,  x  40 ;  6,  maturing  sporo- 
phore, showing  the  development  of  the 
spores,  x  about  100 ;  c,  ripe  spore ;  d, 
hatching  spore  ;  e-h,  stages  in  the  develop- 
ment of  the  zoospores,  x  800.  (a  and  c-h 
after  A.  Lister,  18  ;  6,  after  Famintzin  and 
Woronin,  9.) 


The  spores,  which  at  their  formation  are  uninucleate  (Fig.  1 8,  c), 
are  found,  on  hatching,  to  contain  four  bodies  which  are  apparently 
nuclei  (Fig.  18,  d\  so  it  would  appear  that  division  of  the  nucleus 
occurs  in  the  spore  stage.  When  the  spores  are  brought  into 
water  the  contents  emerges,  becomes  amoeboid,  and  successively 
constricted  into  separate  lobes,  two,  four,  and  eight  in  number 
(Fig.  18,  e-g).  At  the  stage  when  eight  lobes  are  formed  each 
develops  a  flagellum  (Fig.  18,  h),  and  finally,  becoming  distinct 
from  its  fellows,  swims  off  as  a  zoospore.  It  is  evident  that  a 
further  division  of  the  nuclei  must  occur  during  this  process.  The 
zoospore  subsequently  enters  the  amoeboid  stage,  and  the  amoebae 
probably  fuse  to  form  plasmodia,  as  in  the  Endosporeae,  though  the 
process  has  not  been  followed  in  Ceratiomyxa. 

On  comparing  the  somewhat  incomplete  details  of  this  life- 
history  with  those  of  the  Endosporeae,  it  seems  clear  that  the 
abundant  gelatinous  substance  in  which  the  protoplasm  is  contained 
at  the  end  of  the  plasmodium  stage  of  Ceratiomyxa  is,  as  Famintzin 
and  Woronin  pointed  out,  comparable  Avith  the  secreted  material 
which  is  converted  into  the  supporting  structures  of  the 
Endosporeae.  In  Ceratiomyxa  the  spores,  instead  of  lying  in  a 
compact  mass,  contained  in  a  sporangium,  are  distributed  in  a 
superficial  layer,  and  the  sporophore  is  accordingly  disposed  so  as 
to  offer  an  extensive  surface  for  their  support. 

The  division  of  nuclei  prior  to  spore-formation,  found  wherever 
the  development  has  been  followed  in  the  Endosporeae,  has  not  been 
seen  in  Ceratiomyxa,  and  as  this  process  is  frequently  met  with  in 
other  groups  of  Protozoa,  its  apparent  absence  here  is  remarkable. 
It  is  possible  that  this  division  is  represented  by  the  first  of  the 
nuclear  divisions  occurring  within  the  spore ;  in  which  case  the 
spores  of  Ceratiomyxa  would  be  comparable  with  the  masses  into 
which  in  the  Endosporeae  the  protoplasm  separates  about  the 
dividing  nuclei  before  spore-formation,  rather  than  with  the  spores 
of  that  group.  If  this  comparison  were  established,  however,  the 
two  following  divisions  which  occur  in  Ceratiomyxa  before  the 
zoospores  are  formed  would  remain  features  peculiar  to  the  genus.1 


The  other  group  here  included  with  the  Mycetozoa,  the 
Sorophora,  consists  of  forms  the  alliance  of  which  with  the 
Euplasmodida  is  somewhat  remote.  They  live  in  decaying  vege- 
tables and  the  dung  of  herbivorous  animals.  There  is  no  flagel- 
late stage  in  the  life-history,  and  it  is  in  the  form  of  amoebulae 
that  the  active  phase,  with  growth  and  reproduction  by  fission, 
occurs.  At  the  end  of  this  vegetative  phase,  and  only  as  a  pre- 

1  Cf.  the  Postscript  at  the  end  of  this  article. 



liminary  step  to  sporulation,  the  amoebulae  draw  towards  their 
fellows  in  groups,  which  may  be  composed  of  many  hundreds  of 
units,  but  they  maintain  their  individual  distinctness  and  do  not 
fuse  to  form  a  true  plasmodium  as  in  the  Euplasmodida.  Spore- 
production  occurs  in  air,  at  the  surface  of  the  substance  in  which 
the  vegetative  phase  has  been  spent. 

In  Guttulina,  as  well  as  in  the  members  of  the  Dictyosteliaceae,  a 
remarkable  differentiation  occurs  among  the  amoebulae  forming  the 
pseudoplasmodium,  comparable  with  that  characteristic  of  the 

organisation  of  the  Metazoa. 
Some  of  the  amoebulae  secrete  a 
firm  membrane  and  become  joined 
end  to  end  to  form  a  stalk  (Fig. 
1 9,  c  and  d),  attached  below  to  the 
substratum,  and  up  this  the  other 
amoebulae  climb  and  pass  into  the 
encysted  condition  at  the  top  as 
a  naked  cluster  of  spores.  In 
Didyostelium  the  stalk  is  long  and 
simple ;  in  Folysphondylium  it  is 
branched  (Fig.  19,  d). 

Tlie  supporting  structures  of 
the  Sorophora  are  evidently  of  a 
different  nature  from  those  of  the 
Euplasmodida,  in  which  they  are 
not  cellular,  but  formed  as  secre- 
tions of  the  protoplasm. 

It  is,  of  course,  possible  that 
the  pseudoplasmodia  of  the  Soro- 
phora may  represent  a  stage  in 
the  evolution  of  the  true  plas- 
modium, which  in  the  other  group 
is  such  an  important  phase  of  the 
life -cycle;  but  it  appears  more 
probable  that  both  Euplasmodida 
and  the  Sorophora  are  to  be 
derived  from  some  simple  forms 
with  a  life-history  resembling  that 
of  Protomonas  or  Bursulla  among 
the  Proteomyxa. 

Fio.  19. 

a  and  6,  Copromyxa  protea,  Fayod.  a,  a 
simple,  b,  a  branched  form  of  sorus,  slightly 
magnified  (after  Fayod. )•  c  and  d,  Poly- 
sphondylium  violaceurn,  Brefeld.  c,  a  young 
sorus,  seen  in  optical  section,  with  a  mass 
of  amoebae  grouped  round  the  stalk,  and 
others  still  extended  about  the  base,  x  110. 
d,  a  sorus  approaching  maturity.  The  stalk 
has  become  compound.  The  lowest  whorl 
of  secondary  sori  is  complete,  those  above  it 
are  in  varying  degrees  of  completeness,  x  20. 
(After  Brefeld.  From  Zopf,  24.) 

Two  hundred  and  sixty -five 
species  of  the  Euplasmodida  are 
described  in  the  British  Museum  Catalogue  (18);  Zopf  (24) 
enumerated  nine  species  of  Sorophora,  and  Olive  (20),  more 
recently,  twenty. 


The  classificatory  characters  are  mainly  derived  from  the 
sporangia,  the  capillitium  (when  it  is  present),  and  the  spores. 
Some  species  stand  apart  from  their  allies  with  great  distinctness, 
but  in  many  genera  examples  intermediate  in  character  between 
the  species  are  of  common  occurrence,  and  it  is  only  by  large 
experience  of  the  frequency  with  which  the  forms,  as  they  occur 
in  nature,  group  themselves  about  certain  centres  that  a  correct 
idea  of  the  species  can  be  attained. 

The  distribution  of  most  species  appears  to  be,  so  far  as  it  has 
yet  been  determined,  world-wide  in  the  more  humid  parts  of  the 
temperate  and  tropical  regions  of  the  globe,  where  woodlands  and 
forests  offer  conditions  favourable  to  their  existence — a  fact  which 
is  doubtless  dependent  on  the  ease  with  which  the  minute  spores 
are  carried  in  currents  of  air. 

No  Mycetozoa  have  hitherto  been  met  with  in  a  fossil  state, 
though  from  the  degree  of  differentiation  of  the  sporangia  we  cannot 
doubt  that  the  group  is  of  high  antiquity,  and  has  in  past  time,  as 
at  the  present,  played  an  important  part  in  the  disintegration  of 
vegetable  tissues. 

It  is  remarkable  that  no  parasitic  organisms  are  known  to  live 
on  Mycetozoa,  a  fact  which  Stahl  attributes  to  the  readiness  with 
which  foreign  bodies  are  cast  out  by  the  organisms  in  the  plas- 
modial  stage. 

In  writing  this  account  of  the  Mycetozoa  constant  reference  has 
been  made  to  de  Bary's  classical  work  (1-3),  to  the  papers  of 
Cienkowski  (5-8),  and  to  Zopf's  treatise  (24).  But  I  wish  especially 
to  acknowledge  my  obligations  to  the  work  of  my  father,  Mr.  A. 
Lister,  on  their  life -history  and  classification.  So  far  as  I  have 
been  able  to  speak  of  the  biological  aspects  of  the  group  from  my 
own  knowledge,  it  is  mainly  to  the  opportunities  I  have  had  in 
following  this  work  that  I  am  indebted.  The  proof-sheets  of  this 
article  have  been  submitted  to  my  father,  and  I  feel  that  its- 
authority  is  greatly  enhanced  when  I  add,  as  he  allows  me  to  dor 
that  the  conclusions  are  in  the  main  in  accordance  with  his  views. 


The  contents  of  the  spores  develop,  on  hatching,  into  flagellate 
zoospores.  Amoebulae  completely  fused  to  form  the  plasmodium,  which 
is  the  dominant  phase  of  the  vegetative  period. 

Spores  developed  within  sporangia. 

Spores  violet,  or  violet-brown. 


Sporangia  provided  with  lime. 

ORDER  1.  Physaraceae. 

Lime  in  minute,  round  granules. 

A.  Capillitium    a    coarse    network   charged    with    lime    throughout. 
Genus — Badliamia,  Berk.  (Figs.  9  and  10). 

B.  Capillitium    a    delicate    network    of     threads     with    vesicular 
expansions  tilled  with  lime-granules  ( =  lime-knots),     a.  Sporangia  com- 
bined  into   a  convolute  aethalium.     Genus — Fuliyo,   Haller  (Fig.    16). 
P.    Sporangia    single,    scattered,    or    aggregated,     a,    sporangium     wall 
membranous.     Genera — Physarum,  Pers.    (Fig.    13,  a).     Sporangia  sub- 
globose  or  in  the  form  of  plasinodiocarps.     Physarella,  Peck.     Sporangia 
tubular.      6,  sporangium  wall   cartilaginous   throughout,  or  at  the  base 
only.      Genera — Cienkowskia,  Rost.      Sporangia  in  the  form  of  plasmodio- 
carps  ;    Capillitium  with  free  hooked   branches.     Craterium,  Trent   (Fig. 
13,    d).       Sporangia    goblet  -  shaped    or    subglobose.       Leocarpus,    Link. 
Sporangia  ovoid,  glossy. 

G.  Capillitium  without  lime -knots.  Genera — Chondrioderma,  Rost. 
(Fig.  13,  e).  Sporangium  wall  of  two  layers,  more  or  less  combined. 
Trichamphora,  Jungh.  Sporangium  wall  of  one  layer,  fragile  ;  sporangia 

D.  Lime  confined  to  the  stalk  and  columella ;  sporangium  wall 
membranous.  Genus — Diachaea,  Fries. 

ORDER  2.  Didymiaceae. 

Lime  deposited  in  the  form  of  crystals  or  crystalline  discs  on  the 
outer  surface  of  the  sporangium  wall  ;  Capillitium  without  lime-knots. 
Genera — Didymium,  Schrader  (Fig.  17).  Lime  in  crystals  ;  sporangia 
simple.  Spumaria,  Pers.  (Fig.  13,  </).  Lime  in  crystals  ;  sporangia  united 
into  an  aethalium.  Lepidoderma,  de  Bary.  Lime  in  crystalline  discs 
(Fig.  13,  h)  •  sporangia  simple. 


Sporangia  without  deposits  of  lime  ;  Capillitium  dark  brown  or  violet 

ORDER  1.  Stemonitaceae. 

Sporangia  stalked,  the  stalk  extending  within  the  sporangium  as  a 
columella  ;  sporangium  wall  a  single  delicate  membrane,  often  evanescent. 
Genera — Stemonitis,  Gleditsch  (Fig.  1 4,  a-e).  Sporangium  wall  evanescent ; 
.Capillitium  springing  from  all  parts  of  the  elongated  columella,  its  ultimate 
branches  forming  a  superficial  net.  Comatricha,  Preuss.  Like  Stemonitis, 
but  the  branches  of  the  Capillitium  not  forming  a  superficial  net.  Ener- 
thenema,  Bowman.  Sporangium  wall  evanescent ;  columella  reaching  to 
the  apex  of  the  sporangium,  where  it  forms  a  superficial  expansion  from 
which  the  capillitium  springs.  Lamproderma,  Rost.  Sporangium  wall 
somewhat  persistent,  columella  about  half  the  height  of  the  sporangium. 


Clastoderma,  Blytt.  Sporangium  wall  partly  evanescent,  persisting  in  the 
form  of  minute  discs,  at  the  tips  of  the  rigid  capillitium  threads  ;  columella 
ehort  or  none.  Echinostelium,  de  By.  A  minute  colourless  form  with 
long  stalks  and  a  sparsely-branched  spiny  capillitium. 

ORDER  2.  Amaurochaetaceae. 

Sporangia  combined  into  an  aethalium  ;  capillitium  of  irregular 
strands  and  threads,  or  complex.  Genera — Amaurochaete,  Rost.  Capil- 
litium of  irregular  branching  threads.  Brefeldia,  Rost.  Capillitium  of 
horizontal  threads,  with  many-chambered  vesicles. 

Spores  variously  coloured,  never  violet. 


Capillitium  absent,  or  not  forming  a  system  of  uniform  threads  except 
in  Alwisia. 

ORDER  1.  Heterodermaceae. 

Sporangium  wall  membranous,  beset  with  minute  round  granules, 
and  (except  in  Lindbladia)  forming  a  net  in  the  upper  part.  Genera — 
Lindbladia,  Fries.  Sporangia  sessile,  compacted  or  aethalioid,  the  wall 
not  forming  a  net  in  the  upper  part.  Cribraria-,  Pers.  Sporangia  stalked  ; 
sporangium  wall  with  thickenings  in  the  form  of  a  delicate  persistent 
net,  expanded  at  the  nodes.  Dictydium,  Sclirader  (Fig.  14,/).  Sporangia 
stalked  ;  sporangium  wall  with  thickenings  in  the  form  of  longitudinal 
ribs  connected  by  delicate  threads. 

ORDER  2.  Liceaceae. 

Sporangia  solitary,  sessile  or  stalked  ;  sporangium  wall  cartilaginous  ; 
capillitium  and  columella  absent.  Genera — Licea,  Schrader.  Sporangia 
sessile,  globose  or  in  the  form  of  plasmodiocarps.  Orcadella,  Wingate. 
Sporangia  stalked,  furnished  with  a  lid  of  thinner  substance. 

ORDER  3.  Tubulinaceae. 

Sporangium  wall  membranous,  without  granular  deposits  ;  sporangia 
tubular,  compacted  together.  Genera  —  Tubulina,  Pers.  Columella 
absent.  Siphoptychium,  Rost.  A  hollow  pseudo- columella  is  present, 
connected  by  tubular  extensions  with  the  sporangium  wall.  Alvrisia, 
Berkeley  and  Broome.  Sporangia  stalked  ;  with  tubular  threads  attached 
to  the  base  and  apex  of  the  sporangium  wall. 

ORDER  4.  Reticulariaceae. 

Aethalia,  with  the  sporangium  walls  incomplete,  perforated,  and 
forming  a  spurious  capillitium.  Genera  —  Dictydiaethalium,  Rost. 
Sporangium  walls  cap -shaped  above  and  continued  down  to  the  base 
in  four  to  six  straight  threads.  Enteridium,  Ehrenberg.  Walls  of 


convoluted  sporangia  forming  a  tissue  of  interarching  bands.  Reticularia, 
Bulliard.  Walls  of  convoluted  sporangia  forming  tubes  and  folds  with 
numerous  anastomosing  threads. 

ORDER  5.  Lycogalaceae. 

Sporangia  forming  an  aethalium  ;  pseudo-capillitium  consisting  of 
branched  colourless  tubes,  the  remains  of  the  walls  of  the  fused  sporangia. 
Genus — Lycogala,  Micheli. 

Capillitium  a  system  of  uniform  threads. 

ORDER  1.  TricMaceae. 

Capillitium  threads  with  spiral  or  annular  thickenings.  Free  or 
united  into  an  elastic  network.  Trichia,  Haller  (Figs.  11,  12,  and  15,  a-c). 
Capillitium  abundant,  threads  free,  with  spiral  thickenings.  Oligonema, 
Rost.  Capillitium  scanty,  threads  free,  with  imperfect  spiral  thickenings. 
Hemitrichia,  Rost.  (Fig.  15,  d).  Capillitium  threads  combined  into  a  net- 
work, with  spiral  thickenings.  Cornuvia,  Rost.  Sporangia  in  the  form 
of  plasmodiocarps  ;  Capillitium  threads  combined  into  a  network,  with 
annular  thickenings. 

ORDER  2.  Arcyriaceae. 

Capillitium  combined  into  an  elastic  network  with  thickenings  in  the 
form  of  cogs,  half-rings,  spines,  or  warts.  Genera — Arcyria,  Hill  (Fig. 
15,  e-/).  Sporangia  stalked  ;  sporangium  wall  evanescent  above,  persistent 
and  membranous  in  the  lower  third.  Lachnobolus,  Fries.  Sporangia 
sessile,  clustered  ;  sporangium  wall  single,  persistent,  not  thickened  with 
granules.  Perichaena,  Fries.  Sporangia  sessile  or  in  the  form  of  plas- 
modiocarps ;  sporangium  wall  double,  at  least  at  the  base,  the  outer  layer 
thickened  with  angular  granules. 

ORDER  3.  Margaritaceae. 

Sporangia  normally  sessile ;  sporangium  wall  single,  smooth,  trans- 
lucent ;  capillitium  abundant,  not  consisting  of  separate  threads,  nor 
combined  into  a  net.  Genera — Margarita,  Lister.  Capillitium  profuse, 
long,  coiled,  and  hair-like.  Dianema,  Rex.  Capillitium  of  nearly 
straight  threads,  without  spiral  thickenings,  attached  at  both  ends  to  the 
sporangium  walls.  Prototrichia,  Rost.  Capillitium  of  fasciculate  threads, 
attached  above  or  below  to  the  sporangium  wall,  and  spirally  thickened. 

Spores  developed  on  the  surface  of  sporophores. 

ORDER  1.  Ceratiomyxaceae. 

Sporophores  fragile  and  evanescent,  branched  ;  spores  white,  borne 
singly  on  filiform  stalks  arising  from  the  areolated  sporophore.  Genus — 
Ceratiomyxa,  Schroeter  (Fig.  18). 



A  flagellate  stage  is  absent  from  the  life -history.  The  amoebulae 
become  aggregated  prior  to  spore-formation,  but  do  not  fuse  to  form  a  true 
plasmodium.  In  the  more  highly  developed  genera  some  of  the  aggregated 
amoebulae  are  modified  to  form  a  stalk  on  which  the  remainder  are  borne 
after  encystment  in  naked  clusters  (sori). 

ORDER  1.  Guttulinaceae. 

The  aggregation  of  amoebulae,  prior  to  spore-formation,  to  form  the 
pseudo-plasmodium,  is  incomplete  in  Copromyxa.  The  amoebulae  have 
the  Umax  form,  and  the  shape  of  the  sori  is  indefinite. 

Genera — Copromyxa,  Zopf  (Fig.  19,  a  and  6).  Sori  wart-like  or 
spindle-shaped,  1-3  mm.  high,  formed  on  the  surface  of  the  nidus.  None 
of  the  amoebulae  are  differentiated  to  form  a  stalk.  On  horse  and  cow 
dung.  Guttulina,  Cienk.  Some  of  the  aggregated  amoebulae  are  dif- 
ferentiated to  form  a  short  stalk  on  which  the  sorus  is  borne.  On  decaying 
wood  or  horse-dung. 

ORDER  2.  Dictyosteliaceae. 

A  pseudo-plasmodium  is  formed  prior  to  spore-formation.  Some  of 
the  aggregated  amoebulae  are  modified  to  form  a  stalk.  The  sori  have  a 
definite  shape.  Amoebulae  with  short  pointed  pseudopodia.  Genera — 
Didyostelium,  Brefeld.  Stalks  unbranched,  the  spores  without  definite 
arrangement  in  the  sori.  On  dung  of  herbivorous  animals.  A  cram,  van 
Tieghem.  Spores  arranged  in  rows,  like  strings  of  beads,  at  the  ends  of 
the  stalks.  On  beer-yeast.  Polysphondylium,  Brefeld  (Fig.  19,  c  and  d). 
Sori  globular,  on  branched  stalks,  which  attain  1  cm.  in  length.  On 


Since  the  foregoing  account  of  the  Mycetozoa  was  written  papers  .have 
been  published,  in  part  of  a  preliminary  character,  which  appear  to  throw 
light  on  the  nuclear  history. 

In  the  Endosporeae,  Fraulein  H.  Kriinzlin  l  has  described  a  fusion  of 
the  nuclei  in  pairs,  prior  to  the  mitosis  which  precedes  spore-formation,  in 
the  young  sporangia  of  Arcyria,  and  this  result  is  corroborated  by  Jahn.2 
The  number  of  chromosomes  at  this  division  Jahn  believes  to  be  sixteen 
("  8  double  chromosomes  ")  in  Arcyria  (at  least  double  that  which  Jahn 
found  in  the  division  of  the  zoospore  in  other  genera).  In  Fuligo  Harper  3 
found  the  number  to  be  twelve  in  the  mitosis  preceding  spore-formation. 

1  "  Zur  Entwicklungsgescluchte  der  Sporangien  bei  den  Trichien  und  Arcyrien," 
Arch.f.  Protistenkunde,  Bd.  ix.  (1907),  p.  170. 

2  "  Myxomycetenstudien —  6.   Kernverschmelzungen    und    Reduktionsteilungen," 
Eer.  d.  deutsch.  botan.  Gese.llschaft,  Bd.  xxv.  (1907),  p.  23. 

3  "Cell  and  Nuclear  Division  in  Fuligo  varians,"  Botanical  Gazette,  vol.  xxx. 
(1900),  p.  217. 


These  authors  suggest  that  the  fusion  of  nuclei  in  the  young  sporangium 
is  a  long-deferred  karyogamy,  separated  by  the  whole  of  the  plasmodium 
stage,  with  its  many  nuclear  divisions,  from  the  plastogamy  (the  fusion  of 
the  amoebulae)  by  which  the  plasmodium  originates.  They  thus  regard 
the  mitosis  preceding  spore-formation  as  the  one  nuclear  division  in  the 
life-cycle  in  which  the  full  ("somatic")  number  of  chromosomes  is  present. 

Jahn  (I.e.)  and,  subsequently,  Olive1  also  state  that  a  fusion  of  nuclei 
occurs  in  Ceratiomyxa  prior  to  the  formation  of  the  spores.  The  fusion  is 
followed  by  four  according  to  Jahn,  by  two  according  to  Olive,  mitotic 
divisions,  and  the  ripe  spore  is  four-nucleated  (not  one-nucleated,  as  in- 
dicated above  (Fig.  18,  c)). 

It  would  thus  appear  that  there  are,  at  any  rate,  two  mitotic  divisions 
before  spore-formation  in  Ceratiomyxa  and  only  one  in  the  Endosporeae. 
The  spores  are  thus  not  strictly  homologous  in  the  Endosporeae  and 
Exosporeae.  That  of  Ceratiomyxa  is  more  advanced  than  the  spore  of  the 
Endosporeae  in  that  at  least  two  mitotic  divisions  subsequent  to  karyogamy 
have  occurred  (and  the  four  nuclei  thus  arising  are  contained  in  the  spore), 
but  it  is  less  advanced  in  that  no  cleavage  of  the  protoplasm  about  the 
products  of  division  has  taken  place. 


1.  de  Bary,  A.     Die  Mycetozoen.     Zeits.  f.  \viss.  Zool.  vol.  x.  (1860),  p.  88. 

2.  Die  Mycetozoen.     2e  Auflage,  Leipzig,  1864. 

3.  Comparative  Morphology  and  Biology  of  the  Fungi,  Mycetozoa,  and 

Bacteria.     Translation.     Oxford,  Clarendon  Press,  1887. 

4.  Butschli,  0.     Protozoa,  Abth.  g,  Sarcodina.     Bronn's  Thierreich,  Bd.  i. 

5.  Cienkowski,  L.     Die  Pseudogonidien.     Priugsheim's  Jahrbiicher,  i.  p.  371. 

6.  Zur  Entwickelungsgeschichte  der  Myxomyceten.     Pringsheim's  Jahr- 
biicher, iii.  p.  325  (published  1862). 

7.  -          Das  Plasmodium.     Ibid.  p.  400  (1863). 

8.  Beitrage  zur  Kenntniss  der  Monaden.     Arch.  f.  mikr.  Anat.  i.  (1865), 

p.  203. 

9.  Famintzin,  A.,  and  Woronin,  M.    Ueber  zwei neue  Formen  von  Schleimpilzen, 

Ceratium  hydnoides,  A.  and  Sch.,  and  C.  porioides,  A.  and  Sch.     Mem.  de 
1'Acad.  Imp.  d.  Sciences  de  St.  Petersbourg,  ser.  7,  T.  20,  No.  3  (1873). 

10.  Greenwood,  M.,  and  Saunders,  E.  E.     On  the  Role  of  Acid  in  Protozoan 

Digestion.     Journ.  of  Physiology,  xvi.  (1894),  p.  441. 

11.  Jahn,  E.     Myxomycetenstudien — 3.  Kerntheilung  u.  Geisselbildung  bei  den 

Schwarmern  von  Stemonitis  flaccida,  Lister.    Ber.  d.  deutschen  botanischeu 
Gesellschaft,  Jahrg.  1904,  Bd.  xxii.  Heft  2. 

12.  Krukenberg.    Ueber  ein  peptisches  Enzym  im  Plasmodium  der  Myxomyceten 

und  im  Eidotter  vom  Huhne.      Uuters.  aus  d.  physiol.  Inst.  in  Heidel- 
berg, 1878,  ii.  p.  273. 

1  "  Cytological  Studies  in  Ceratiomyxa,"  Trans.  Wisconsin  Academy  of  Science, 
Arts,  and  Letters,  vol.  xv.  (1907),  pt.  2,  p.  753  ;  and  "Evidences  of  Sexual  Repro- 
duction in  Slime  Moulds,"  Science  (N.S.),  vol.  xxv.  (1907),  p.  266. 


13.  Lcinkcster,  E.  R.     Article  "Protozoa"  in  Encyclopaedia  Britannica,  1891. 

14.  Lister,    A.      Notes    on    the    Plasmodiurn    of    Badhamia    utricularis   and 

Brefeldia  maxima.     Ann.  of  Bot.  vol.  ii.  No.  5  (1888). 

15. On  the  Ingestion  of  Food  Material  by  the  Swarm-Cells  of  Mycetozoa. 

Journ.  Linn.  Soc.  (Botany),  vol.  xxv.  (1889),  p.  435. 

16.  -      -     On  the  Cultivation  of  Mycetozoa  from  Spores.     Journ.  of  Botany, 

Jan.  1901. 

17.  —     -     On  the  Division  of  Nuclei  in  the  Mycetozoa.     Journal  of  the  Linnean 

Soc.  (Botany),  xxix.  (1893). 

18. A  Monograph  of  the  Mycetozoa.     Brit.  Museum  Catalogue.     London, 


19.  Metschnikoff,  E.     Recherches  sur  la  digestion  intracellulaire.     Annales  de 

1'Institut  Pasteur,  1889,  p.  25. 

20.  Olive,  E.    W.      Monograph  of  the  Acrasieae.     Proc.   Boston  Soc.   of  Nat. 

History,  vol.  xxx.  No.  6  (1902). 

20«.  Peiuird,  E.    ]5tude  sur  la   Chlamydomyxa   montana.      Arch.   f.   Protisten- 
kunde,  Bd.  iv.  Heft  2  (1904),  p.  296. 

21.  Plenge,    H.      Ueb.    d.    Verbindungen    zwischen   Geissel    u.    Kern    bei    d. 

Schwarmerzelleu  d.   Mycetozoen   .    .   .   Verb.  d.   nat.-hist.  med.  Vereins 
zu  Heidelberg,  N.F.  Bd.  vi.  Heft  3,  1899. 

22.  Stahl,    E.      Zur    Biologic   der    Myxomyceten.       Bot.    Zeitung,  .Jahrg.    42 

(1884),  pp.  145,  161,  and  187. 

•23.  Strasburger,   E.      Zur    Entwickelungsgeschichte   d.   Sporangien   v.  Trichia 
fallax.     Botanische  Zeitung,  1884. 

24.  Zopf,    W.      Die   Pilzthiereo   der    Schleimpilze.      Schenk's    Handbuch    der 

Botanik,  1887. 

25.  Zur   Kenntniss  der   Labyrinthuleen,    einer   Familie   der   Mycetozoa. 

Beitrage  zur  Physiologie  u.  Morphologic  niederer  Organismen.     Heft  2 
(1892),  p.  36,  Leipzig. 

THE   PEOTOZOA  (continued) 


GYMNOMYXA  (Homokaryota),  with  lobate  or  pointed  unbranched 
pseud opodia  without  an  axis  and  with  one  or  more  definite  nuclei. 

In  a  large  number  of  the  characteristic  genera  of  Lobosa  the 
body  consists  of  a  small  plastid  of  protoplasm  protruding  a  few 
lobate  pseudopodia  by  means  of  which  a  slow  progression  is 
effected,  and  exhibiting  one  nucleus  and  a  contractile  vacuole. 

In  addition  to  these  characteristic  forms,  however,  other  genera 
must  be  included  in  the  same  class  in  Avhich  the  body  is  protected 
by  membranous  or  rigid  shells  (Thecamoebida),  with  radiating  and 
pointed  pseudopodia  (Trichosphaerium,  etc.),  with  two  (Arcella),  or 
numerous  nuclei  (Pelomyxa),  and  with  no  contractile  vacuole 
(Endamoeba,  etc.). 

In  many  Lobosa,  such  as  Amoeba  terricola  (Penard  [20])  and 
others,  the  superficial  protoplasm  secretes  a  membranous  envelope 
through  which  the  pseudopodia  may  be  protruded  or  particles  of 
food  ingested.  In  Trichosphaerium  the  envelope  is  relatively 
thick,  gelatinous  in  texture,  and  provided  with  a  series  of  very 
delicate  radiating  spicules,  mainly  composed  of  carbonate  of 
magnesia.  Spicules  similar  to  these  are  also  found  in  the  ecto- 
plasm of  Amoeba  pilosa  (Cash),  in  which  no  true  membrane  is 
formed.  In  Dinamoeba  (Leidy)  the  spicules  occur  in  a  hyaline 
jelly  that  surrounds  the  body. 

In  the  Thecamoebida  a  definite  shell  is  formed  through  which 
the  pseudopodia  cannot  penetrate.  In  this  case  the  pseudopodia 
can  protrude  only  through  a  definite  and  permanent  mouth  or 
pore  in  the  shell,  which  it  is  convenient  to  call  the  pylome  (Hartog). 

In  some  forms  of  Amoeba  and  in  other  genera  there  is 
often  seen  an  apparent  differentiation  of  the  protoplasm  into  a 
clear  outer  layer,  called  the  ectoplasm,  and  a  more  granular  and 
more  fluid  central  substance  called  the  endoplasm.  This  appear- 
ance is  more  clearly  defined  when  the  protoplasm  is  very  active 
and  several  pseudopodia  are  protruded.  In  the  quiescent  stages 
and  conditions  of  life  the  ectoplasm  usually  disappears  or  becomes 
extremely  attenuated,  and  in  species  or  forms  with  only  one  or  two 

1  By  Prof.  S.  J.  Hickson,  M.A.,  F.R.S. 


pseudopodia  it  can  be  clearly  observed  only  on  the  pseudopodia 
themselves  (Fig.  12,  2).  It  seems  probable,  therefore,  that  in  the 
Lobosa  there  is  no  true  differentiation  of  the  cytoplasm,  and  that 
the  appearance  known  as  ectoplasm  is  only  due  to  the  temporary 
withdrawal  of  metaplasmic  particles  from  the  superficial  parts  of 
the  active  cytoplasm. 

At  the  surface  of  an  Amoeba  there  may  always  be  seen  a  dark 
border  which  has  the  appearance  of  a  very  thin  pellicle.  This 
pellicle  may  be  traced  on  the  sides  of  the  pseudopodia,  but  fades 
away  towards  their  extremities,  becoming  extremely  attenuated  at 
the  active  terminal  point.  Immediately  below  this  pellicle  there 
is  a  layer  of  very  hyaline  ectoplasm.  In  carefully  prepared  sections 
the  hyaline  ectoplasm  is  found  to  be  not  strictly  homogeneous,  but 
to  possess  an  alveolar  structure  similar  in  general  characters  to  that 
of  other  forms  of  protoplasm.  At  the  actual  surface  there  is  a 
single  layer  of  alveoli,  in  which,  as  in  artificially  prepared  oil  foams, 
the  sides  vertical  to  the  surface  are  parallel,  or  almost  parallel,  to 
each  other,  giving  the  appearance  of  a  row  of  fine  vertical  striae.  It  is 
apparently  this  marginal  alveolar  layer  which  constitutes  the  pellicle. 

The  movements  of  an  Amoeba  may  be  best  interpreted  on  the 
basis  of  the  alveolar  hypothesis  of  the  structure  of  protoplasm. 

The  protrusion  of  a  pseudopodium  begins  with  a  lowering  of 
the  surface  tension  of  the  marginal  alveolar  layer  over  a  small  area 
on  the  surface.  This  is  followed  by  a  flow  of  endoplasm  towards 
the  area  of  reduced  surface  tension.  It  has  been  suggested  that 
the  initial  stages  are  accompanied  by  a  rupture  of  some  of  the 
alveoli  at  the  surface,  which  liberates  a  fluid — the  enchylema — and 
that  this  causes  a  local  diminution  of  the  surface  tension.  It  is 
possible  that  the  release  of  enchylema  may  continue  during  the 
whole  of  the  process  of  the  protrusion  of  a  pseudopodium,  and 
stop  when  the  pseudopodium  comes  to  rest.  During  the  active 
protrusion  of  a  pseudopodium  there  may  be  observed  a  rapid 
centrifugal  flow  of  endoplasm  towards  the  peri- 
phery, called  the  axial  stream.  At  the  apex  this 
stream  spreads  outwards  like  a  fountain,  and  is 
continued  as  return  currents  on  the  surface.  Similar 
fountain-like  currents  have  been  observed  in  the 
movements  of  various  artificially  prepared  foams, 
but  in  the  living  protoplasmic  pseudopodium  the 
velocity  of  the  return  currents  diminishes  more  FIG.  i. 

rapidly  and  soon  comes  to  rest  (Fig.  1).  In  an  Diagram  to  show 
Amoeba  such  as  A.  Umax,  in  which,  as  a  rule,  only  °  ° 

one   pseudopodium   is  formed,   there   is   a  reverse 
fountain  current  at  the  posterior  end,  the  particles  at 
the  surface  flowing  towards  the  axis  and  joining  in  the  axial  stream 
flowing  in  the  direction  of  the  advancing  pseudopodium.     But  in 


this  case  the  actual  posterior  end  is  not  involved  in  the  current,  and 
by  the  increase  of  surface  tension  becomes  folded  or  wrinkled,  giving 
sometimes  an  appearance  of  several  small  pseudopodia  (Fig.  12,  2). 
In  polypodious  Amoebae  similar  reverse  currents  may  be  ob- 
served in  retreating  pseudopodia,  and  in  areas  of  the  body 
that  are  supplying  materials  for  the  axial  streams  of  advancing 

Nucleus. — The  nucleus  of  the  Lobosa  in  its  resting  condition 
usually  exhibits  a  well-defined  membrana  liniitans.  The  chromatin 
is  in  the  form  of  a  number  of  spherical  or  irregular  particles  frequently 
collected  together  round  the  periphery,  leaving  a  more  or  less  clear 
space  in  the  centre.  In  some  cases  a  very  delicate  network  of 
fibrils  has  been  observed,  which  is  regarded  as  linin  (Fig.  2). 

One  or  more  nucleoli  composed  of  a  substance  which  differs 
chemically  in  some  of  its  reactions  from  chromatin 
may  or  may  not  be  present. 

In  Paramoeba  eilhardi  there  occurs  a  deeply 
staining  body  in  proximity  to  the  nucleus,  which 
was  termed  by  Schaudinn  (25),  who  described  it, 
the  "  nebenkorper  "  (Fig.  4,  c).  This  body  divides 
previous  to  the  division  of  the  nucleus,  and  the 
two  parts  take  up  a  position  at  opposite  poles  of 
the  spindle.  This  body  is  usually  regarded  as  a  "nucleolar  cen- 
trosome."  A  body  corresponding  to  this  has  also  been  found  by 

FIG.  2. 

Nucleus  of  Pelomyxa. 
(After  Bott.) 


ch,  ' 

Fio.  3. 

Dividing  nucleus  of 
Amoeba  Umax,  m.l,  the 
meinbraua  liini  tans  of  the 
nucleus  ;  c,  the  nucleo- 
lar centrosome  ;  eh,  the 
chromosomes  arranged 
iu  an  equatorial  band. 
(After  Vahlkampf.) 

FIG.  4. 

The  resting  nucleus 
(.V)  and  "nebenkorper" 
(c)  of  Paramoeba  eilhardi. 
(After  Schaudinn.) 

Fio.  5. 

The  nucleus  of  the 
same  species  dividing. 
The  "nebenkorper"  (c) 
has  divided  into  two 
parts,  which  occupy  a 
position  at  the  foci  of  the 
central  spindle,  eh,  the 
chromosomes  arranged 
in  an  equatorial  band. 
(After  Schaudinn.) 

Vahlkampf  in  the  division  of  the  nucleus  of  Amoeba  Umax  (Fig.  3),2 
but  in  this  case  the  nucleolar  centrosome  lies  within  the  nuclear 

1  The  subject  of  amoeboid  movements  has  of  recent  years  attracted  the  attention 
of  many  observers.     The  views  expressed  by  Biitschli  (Investigations  on  Microscopic 
Foams,    etc.,    transl.    by    Minchin,    1894)   have   been   opposed    by    Jennings    (14), 
but  Jennings'  views  have  been  more  recently  criticised  by  Rhunibler  (23). 

2  For  a  discussion  on  the  nature  of  these  bodies,  see  Goldschmidt  and  Popoff, 
Archivf.  Protist.  viii.,  1907,  p.  321. 


Although  the  presence  of  a  defined  nucleus  is  regarded  as  one 
of  the  characters  of  the  class,  it  has  been  shown  that  the  nuclei 
sometimes  disintegrate  and  discharge  their,  chromatin  into  the 
cytoplasm  as  scattered  granules.  This  occurs  as  a  result  of 
starvation  in  Pelomym  (Bott  [2]),  and  as  an  antecedent  to  the 
formation  of  sexual  or  reproductive  nuclei  in  Endamoeba. 

Chromidia. — In  addition  to  the  chromatin  contained  within  the 
boundaries  of  the  nuclei,  there  may  be  present  in  the  cytoplasm  of 
many  Lobosa  irregular  scattered  granules  or  a  fine  network  of  a 
substance  which  gives  the  same  reactions  and  is  probably  of  the 
same  nature  as  chromatin. 

In  some  cases,  Difflugia  (Fig.  6),  the  network  entirely  envelops 
the  nucleus  or  nuclei,  but  in  others  it  is  separated  from  the  nuclei, 
Arcella,  Cochliopodimn,  etc.  (Figs.  19  and 
21),  by  a  halo  of  clear  protoplasm. 

These  granules  are  called  the 
chromidia,  and  the  network  is  called  the 
chromidial  network  (Fig.  6,  ch).  The 
chromidia  may  arise  by  the  migration  of 
particles  of  chromatin  from  the  nucleus 
into  the  cytoplasm  or  by  the  disintegra- 
tion of  nuclei,  but  it  seems  probable  that 
in  some  cases  they  may  arise  de  now 
in  the  cytoplasm. 

The  fate  of  the  chromidia  is  varied. 
They  may  either  give  rise  to  the  nuclei 

nf    <y;iTnpfp<3    nr    nf    <5\virm  «innvp<5    (Tpnirn 
'I    gametes  S    (^eniW- 

v>/.?is\  or  they  may  accumulate  in  groups   by the  chromidial  network  (ch).   r, 

*9       n  .  .»          J  i   .        *       i        pylome;    th,    theca    wall.      (After 

and    give    rise    to    new   nuclei    of    the   Hertwig.) 

ordinary  type  in  the  cytoplasm  (Arcella, 

I'elomyxa),  in  which  cases  they  are  called  Idiochromidia.     Or,  on 

the  other  hand,  they  may  be  associated  with  the  assimilating  or 

vegetative  functions  of   the  cytoplasm  and  disappear  when  their 

activity  is  exhausted,  in  which  case  they  are  called  Trophochromidia. 

Refringent  and  Crystalline  Bodies. — In  many  Lobosa  crystalline 
bodies  and  vesicles  containing  a  strongly  refracting  substance  or 
fluid  occur  in  great  numbers  in  the  cytoplasm.  Very  often  they 
are  far  more  numerous  and  conspicuous  during  the  stages  and 
conditions  of  life  when  active  feeding  is  in  progress  than  in 
conditions  of  starvation  or  reproduction.  They  are  usually 
regarded  as  of  the  nature  of  reserve  food  materials. 

In  Amoeba  dofleini,  Neresheimer  (18)  found  that  the  crystalline 
body,  proteid  in  composition,  is  associated  with  a  trophochromidium 
which  is  probably  the  active  principal  of  its  formation.  Veley  (34) 
has  shown  that  the  refracting  bodies  of  Pelomym  are  proteid  in  nature. 

On    the    other   hand,  Zuelzer  (35}  has    described    the   bodies 

FIG    C. 

Section    through    Difflugia    sp.  ? 
showing  the  nucleus  (A')  surrounded 


formed    by  the    trophochromidia    of    Difflugia  as  carbohydrate  in 
composition,  but  the  crystalline  and  other  bodies  of  Trichosphaerium, 

according  to  Schaudinn,  give  differ- 
ent reactions. 

Vacuoles.  —  In  nearly  all  the 
freshwater  and  marine  Lobosa  there 
is  at  least  one  contractile  vacuole. 
In  Pelomyxa  and  some  of  the  Theca- 
moebida,  however,  contractile  vac- 
uoles  have  not  been  found.  The 
endoparasitic  Amoebida  have  no 
contractile  vacuoles.  In  addition 
to  the  contractile  vacuole  numerous 
non-  contractile  vacuoles  containing 
a  fluid  of  unknown  constitution 

FIG.  7. 

re,  refringent  proteid  bodies  ;  b,  symbi- 
otic  bacteria  (Cladothnx)  ;  chr,  scattered 
chromidia  ;»,  water  vacuoles.  (After  Bott.) 


occur  jn  the  endoplasm. 

When    a   particle  of    food    OCClirs 

in    a    non-contractile   vacuole    it.  is 

usually  called  a  food-vacuole,  and  the  fluid  in  such  vacuoles  has 
been  shown  in  some  cases  to  be  slightly  acid  in  reaction  and 
probably  contains  a  digestive  ferment. 

In  Arcella  and  in  other  Thecamoebida  vacuoles  containing  a 
gas  are  found  within  the  shell.  These  vacuoles  serve  hydrostatic 

Reproduction  —  Fission,  —  Reproduction  by  fission  has  been 
proved  to  occur  as  a  normal  process  in  many  of  the  genera  of 
Lobosa.  In  Amoeba  and  allied  genera  the  result 
of  fission  is  a  pair  of  equal  -sized  daughter 

r*     a~±-\ 

Fio.  S. 

Daetylosphaera  polypodia,  M.  Schultze,  in  three  successive  stages  of  division.  The  stages 
indicated  occupied  fifteen  minutes,  a,  nucleus ;  b,  contractile  vacuole.  (After  F.  B. 

Amoebae.      In   Pelomyxa,   Trichosphaerium,  and  probably  in  other 
multi nucleated  Gymnamoebida,  fission  may  be  unequal. 

In  the  Thecamoebida  one  of  the  individuals  of  the  act  of  fission 
retains  the  shell,  and  the  other  sooner  or  later  forms  a  new  shell 
which  is  usually  larger  than  that  of  the  parent. 

THE  LOB  OS  A  73 

The  process  of  fission  is  usually  preceded  by  division  of  the 
nucleus,  or  in  the  binucleate  Amoebae  of  both  nuclei. 

In  some  species  (Amoeba  binucleata  and  Paramoeba  eilhardi, 
Schaudinn  (Figs.  4  and  5),  A.  Umax,  Vahlkampf,  and  Amoeba  proteus, 
Awerinzew)  the  division  of  the  nucleus  shows  some  of  the  charac- 
ters of  ordinary  mitosis.  The  chromatin  is  collected  together  into 
a  large  number  of  short  chromosomes  arranged  in  an  equatorial 
row.  They  then  divide  and  travel  in  two  equal  parties  along 
faintly  stained  and  nearly  parallel  lines,  supposed  to  be  of 
the  nature  of  linin,  towards  the  opposite  poles  of  the  nucleus, 
where  they  unite  to  form  the  chromatin  network  of  the  daughter 
nuclei.  The  threads  of  the  figure  do  not  always  converge  at  the 
poles  to  a  focal  point,  and  as  a  general  rule  it  is  doubtful  whether 
structures  exactly  similar  to  the  centrosomes  of  the  metazoan  nuclei 
occur.  Centrosomes,  however,  have  been  described  and  figured 
in  the  division  of  the  nuclei  of  Pelomyxa  (Bott  [2],  Fig.  11,  a). 

Notwithstanding  the  evidence  of  a  primitive  kind  of  mitosis  in 
the  division  of  the  nuclei  in  these  and  other  species,  the  division  of 
the  nucleus  of  Amoeba  crystalligera,  of  A.  hyalina,  of  Dactylosphaera 
polypodia,  and  of  Endamoeba  coli  (Schaudinn)  is  amitotic. 

In  Pelomyxa  and  Trichosphaerium  fission  usually  consists  in  the 
pinching  off  of  globules  from  the  body,  each  containing  a  few 
nuclei.  These  globules  rapidly  assume  the  characters  of  the 
parent;  they  increase  in  size  and  the  number  of  the  nuclei  is 
.augmented.  This  process  may  be  regarded  as  a  case  of  unequal 
fission  or  of  gemmation,  but  it  appears  to  differ  from  the  equal 
fission  of  some  species  of  Amoeba  in  the  respect  that  antecedent 
•division  of  the  nuclei  is  not  an  essential  preliminary  to  division  of 
the  cytoplasm.  In  a  large  multinucleate  form  of  Amoeba  proteus, 
Stole  (31)  has  found  that  division  of  the  nuclei  may  or  may  not 
take  place  before  fission ;  and  in  some  cases  some  of  the  nuclei 
divide  and  others  do  not  before  an  act  of  fission. 

Encystment  and  Spore-Formation. — It  is  now  known  that  many 
of  the  Gymnamoebida  periodically  undergo  a  process  of  encystment 
in  which  the  pseudopodia  are  withdrawn,  the  body  becomes  more 
or  less  spherical,  and  one  or  more  tough  membranes  are  formed 
which  entirely  surround  and  protect  the  animal.  In  some  cases 
these  cysts  appear  to  be  of  the  nature  of  resting  cysts  (Amoeba 
Umax,  Vahlkampf  [33]),  the  organism  emerging  from  the  broken 
•cyst-wall  with  the  same  characters  it  possessed  previous  to  cyst- 
formation.  The  formation  of  resting  cysts  probably  occurs  in  all 
the  Thecamoebida.  In  many  cases,  however,  the  encystment  is 
accompanied  by  complicated  nuclear  changes  and  divisions  followed 
by  division  of  the  cytoplasm,  and  a  swarm  of  minute  spores  that 
.are  often  very  different  in  character  from  the  parent  form  are 
hatched  out  when  the  cyst-wall  breaks  down. 



In  the  case  of  Endamoeba  coli  (Schaudinn  [36]),  for  example, 
the  uninucleate  amoeboid  form  discharges  all  foreign  bodies  from 
its  cytoplasm  and  becomes  surrounded  by  a  clear,  soft,  jelly-like 
envelope.  Within  the  cyst-wall  it  divides  into  two  equal  parts 
each  with  a  single  nucleus,  and  these  two  parts  remain  separate 
for  a  considerable  time.  The  two  nuclei  then  fragment,  their 
chromatin  being  scattered  in  the  cytoplasm  as  isolated  chromidia. 
The  two  nuclei  are  now  reconstructed,  but  each  reconstructed 
nucleus  is  relatively  poor  in  chromatin.  Each  of  these  nuclei  now 
divides  into  two  by  a  primitive  kind  of  mitosis ;  one  of  them  from 
each  half-amoeba  is  rejected  as  a  polar  nucleus  and  the  remaining 
one  divides  again.  At  this  stage  in  the  process  the  protoplasm 
contracts,  the  gelatinous  membrane  disappears,  and  the  cyst 
is  surrounded  by  a  harder  membranous  wall.  The  daughter 
nuclei  of  this  mitosis  conjugate  reciprocally  with  the  daughter 
nuclei  of  the  other  half-amoeba,  and  each  of  the  two  zygote  nuclei 
thus  formed  divides  twice.  The  eight  nuclei  thus  formed  become 
the  nuclei  of  eight  amoebulae  which  escape  from  the  cyst. 

In  Amoeba  proteus  also,  according  to  Scheel,  division  of  the 
nucleus  and  cytoplasm  takes  place  during  the  encystment,  and 

FIG.  9. 

A,  cyst  of  Amoeba  proteus  ;  abc,  cyst-wall ;  d,  gelatinous  envelope ;  K,  F,  nuclei ;  0,  albu- 
minous bodies,  x  300.  (After  Scheel.)  B,  cyst  of  Endamoeba  blattae,  with  25  nuclei.  (After 

a  swarm  of  small  amoebulae  emerge  from  it  when  the  cyst  breaks 
down.  In  this  case,  however,  there  is  no  evidence  that  any  form  of 
nuclear  conjugation  takes  place  during  the  encystment. 

Conjugation. — Although  the  complete  life-history  of  only  a  few 
species  of  the  Lobosa  has,  at  present,  been  fully  worked  out,  the 
evidence  is  accumulating  to  justify  the  conclusion  that  a  process  of 
conjugation  is  an  essential  condition  for  the  completion  of  the  life- 
cycle  in  all  forms.  The  process  of  conjugation  has  not  yet  been 
observed  in  Amoeba  proteus  or  in  any  of  its  allies.  Nuclear  con- 
jugation accompanied  by  fusion  of  the  cytoplasm  occurs  during, 
encystment  in  Endamoeba  coli. 


In  Pelomyxa  (Bott  [2])  amoeboid  isogametes  are  discharged 
from  the  body  with  a  nucleus  formed  in  a  manner  that  suggests 
that  the  number  of  the  chromosomes  is  reduced  (infra,  p.  76). 
These  gametes  conjugate  to  form  a  zygote  (Fig.  10),  which  may 
subsequently  encyst. 

In  Trichosphaerium  (Schaudinn  [26])  a  large  number  of 
biflagellate  isogametes  escape  from  the  cyst  and  by  exogamous 
conjugation  form  zygotes  which  become  amoeboid  in  character. 

Biflagellate  isospores  arise  from  the  cystic  stage  of  Paramoeba 
eilhardi,  but  there  is  no  evidence,  at  present,  to  show  that  they 

In  Centropyxis  (Schaudinn  [27])  heterogametes  are  formed 
which  have  a  shell.  After  conjugation  the  zygote  escapes  from 
the  shell  and  forms  a  new  one  like  that  of  the  adult  individual. 

Life-History. — The  recent  rapid  advance  in  our  knowledge  of 
the  life-history  of  Lobosa,  due  in  large  measure  to  the  researches 
of  Schaudinn  and  R.  Hertwig,  suggests  that  in  all  cases  the 
developmental  cycle  that  is  passed  through  is  both  complicated  and 

In  order  to  illustrate  the  general  character  of  these  life- 
histories,  four  examples  may  be  taken  for  description. 

Endamoeba  coli  is  found  in  the  upper  part  of  the  human  large 
intestine,  but  unlike  Endamoeba  histolytica  it  does  not  appear  to  be 
the  cause  of  or  associated  with  any  particular  form  of  disease.  It 
undoubtedly  occurs  in  perfectly  normal  and  healthy  hosts. 

During  the  ordinary  vegetative  life  in  the  intestine  it  multiplies 
by  simple  fission  with  amitotic  division  of  the  nucleus.  Occasionally 
schizogony  occurs,  when  the  nucleus  divides  into  eight  by  successive 
mitoses  and  each  of  these  nuclei  becomes  the  nucleus  of  a  daughter 
amoebula.  After  a  certain  period  of  vegetative  life,  the  normal 
duration  of  which  has  not  been  estimated,  the  uninucleated  amoebae 
become  encysted,  and  in  that  condition  are  passed  into  the  lower 
part  of  the  large  intestine,  and  so  to  the  exterior  with  the  faeces. 
The  complicated  divisions  and  the  conjugation  of  the  nuclei  during 
and  antecedent  to  complete  encystment  have  already  been  described. 
Many  of  the  cysts  undoubtedly  perish,  but  the  cysts  with  eight 
nuclei  when  swallowed  by  another  host  will  give  rise  to  eight 
amoebulae  which  infest  the  intestine  of  the  new  host.  The  cysts 
with  more  than  eight  nuclei  that  are  sometimes  found  in  the  faeces 
are,  according  to  Schaudinn,  degenerating  cysts,  and  never  give  rise 
to  active  amoebulae. 

In  Trichosphaerium,  a  marine  rhizopod  with  peculiar  radiate 
pseudopodia  and  many  nuclei,  there  are  two  phases  in  the  life-cycle. 
In  the  first  phase  the  gelatinous  investment  is  armed  with  radiating 
apicules.  It  reproduces  itself  in  this  phase  by  simple  binary  or  by 
multiple  fission,  the  pseudopodia  being  previously  Avithdrawn.  In 


the  second  phase,  in  which  the  radiating  spicules  do  not  occur, 
reproduction -may  also  occur  in  a  manner  similar  to  that  of  the  first 
phase,  but  at  the  conclusion  of  vegetative  growth  the  pseudopodia 
are  withdrawn,  all  foreign  bodies  and  excreta  are  expelled,  and  a 
cyst  is  formed.  The  nuclei  then  divide  rapidly  by  repeated  mitoses 
to  form  an  immense  number  of  minute  nuclei.  These  nuclei  become 
the  nuclei  of  minute  biflagellate  swarm-spores  (gametes),  which  escape 
from  the  gelatinous  investment  of  the  cyst,  and  after  conjugation 
give  rise  to  small  individuals  of  the  first  phase. 

In  Pelomj/xa,  a  multinucleate  freshwater  rhizopod  (Fig.  14),  repro- 
duction is  effected  by  simple  or  multiple  fission  during  the  vegetative 

period  of  life,  but  at  certain  times, 
after  a  complicated  series  of 
nuclear  divisions  in  which  a  re- 
duction in  the  number  of  chro- 
mosomes occurs,  uninucleated, 
heliozoan-like  swarm-spores  escape 
which  conjugate  to  form  a  zygote, 
and  this  encysts.  From  the  cyst 
a  uninucleated  amoebula  escapes, 
which  by  growth  and  multipli- 
cation of  the  nucleus  gradually  assumes  the  typical  Pelomyxa  form. 

In  the  preparation  of  the  nuclei  for  the  formation  of  the  gametic 
nuclei,  a  considerable  part  of  the  chromatin  is  discharged  into  the 
cytoplasm,  and  from  that  which  remains  eight  chromosomes  are 
formed  on  the  equatorial  band  of  a  central  spindle  (Fig.  11,  a).  Two 
successive  divisions  take  place,  the  first  of  which  is  regarded  as  a 
reduction  division,  and  the 
second  as  an  equation  division. 
The  chromatin  of  the  four 
chromosomes  of  this  last 
division  collect  together  in 
two  lumps,  and  a  transparent 
globular  vacuole  appears  in 
their  immediate  neighbour- 
hood. This  vacuole  gradually 
fills  with  minute  granules 

Fio.  10. 

Zygote  of  Pelomyia  palustris.    a,  encysted. 
I,  after  escape  from  the  cyst.    (After  Bott.) 


FIG.  11. 

Nuclear  formation  in  Pdomyxa,    a,  the  spindle 
of  the  reduction  division  with  eight   chromo- 
somes,   b,  the  nucleus  (AT)  of  the  gamete  forming 
in  a  clear  vacuole.    ch,  the  chromatin  lumps  of 
which    rapidly  increase    in    Size     the  last  nuclear  division.    (After  Bott.) 

and  gives  rise  to  the  nucleus 

of  the  gamete  (Fig.  11,  b).     The  chromatin  lumps  at  the  same  time 

dwindle  and  eventually  disintegrate. 

In  Centropyxis,  one  of  the  Thecamoebida,  binary  fission  occurs 
by  the  protrusion  and  division  of  the  protoplasm  preceded  by 
amitotic  division  of  the  nucleus.  One  portion  of  the  divided  proto- 
plasm with  one  nucleus  returns  to  the  old  shell,  the  other  forms  a 
new  shell  but  of  a  larger  size.  It  does  not  seem  certain  Avhether 


the  individual  retained  by  the  old  shell  is  or  is  not  capable 
of  further  reproduction,  but  the  occurrence  of  an  immense  number 
of  empty  shells  in  cultures  of  Centropyxis  and  its  allies  suggests  that 
it  may  die  after  one  act  of  fission.  The  individual  that  has  formed 
a  new  and  larger  shell,  however,  certainly  divides  again,  giving  rise 
by  a  similar  process  to  a  daughter  individual  with  a  still  larger 
shell.  When  by  these  processes  of  fission  the  full  size  is  reached, 
the  nucleus  degenerates,  after  giving  rise  to  an  expanded  chromidial 
network  which,  with  about  two-thirds  of  the  protoplasm,  protrudes 
from  the  mouth  of  the  shell,  is  pinched  off,  and  escapes.  The 
remaining  one-third  of  the  protoplasm  and  the  degenerate  nucleus 
that  remain  in  the  shell  probably  die. 

The  escaped  protoplasm  may  give  rise  to  one  of  two  broods  of 
gametes.  In  one  brood  (the  megagametes)  the  chromidia  give  rise 
to  a  nucleus  and  the  protoplasm  forms  a  shell ;  in  the  other,  after 
a  nucleus  is  formed  from  the  chromidia  and  a  shell  is  formed  as 
in  the  first  brood,  a  division  into  four  individuals  (the  microgametes) 
takes  place,  and  each  of  these  escapes  and  forms  a  small  shell. 
Conjugation  takes  place  between  the  larger  and  smaller  individual 
gametes,  and  the  zygote  escapes  to  form  a  new  shell  like  that  of 
the  parent. 

ORDER  Gymnamoebida, 

The  surface  of  the  body  either  naked  or  provided  with  a 
thin  flexible  membrane  through  which  the  pseudopodia  can  be 

Genera  Amoeba. — The  generic  name  Amoeba  is  often  applied 
to  any  naked  amoeboid  organism  without  reference  to  its  subsequent 
or  antecedent  history.  As  our  knowledge  of  the  natural  history 
of  the  simpler  Protozoa  widens  it  becomes  more  evident  that  the 
generic  name  should  be  used  only  in  a  restricted  sense.  The  limits- 
we  place  upon  the  use  of  the  generic  name  can  only  be  regarded 
as  provisional.  Further  investigations  may  well  prove  that  the 
species  now  included  in  the  genus  Amoeba,  ought  to  be  still  further 
separated  into  subgeneric  or  generic  groups. 

The  characters  of  the  genus  may  be  summarised  as  follows  : — 
Solitary  Gymnamoebida,  with  a  few  short  blunt  pseudopodia,  a 
single  contractile  vacuole,  and  one  or  more  nuclei.  No  membrane 
covering  the  body  in  the  trophic  phase  of  life.  Freshwater  or 

Nine  or  ten  distinct  species  have  been  described  from  fresh 
water  in  this  country  (Cash).  They  are  usually  found  in  the  mud 
at  the  bottom  of  ponds  or  creeping  on  submerged  vegetation. 
Some  of  the  rarer  forms  are  found  in  Sphagnum  bogs.  One  of  the 
commonest  species  is  Amoeba  proteus  (Fig.  12,  5),  a  species  capable 
of  considerable  variation  in  form,  but  usually  exhibiting  several 


digitiform  pseudopodia.  In  this  species  there  may  be  either  one  or 
many  nuclei.  It  may  reach  a  size  of  200  /A  in  diameter.  A.  guttula 
(Fig.  12,  4)  is  another  very  common  species  of  small  size,  30  /A,  which 
shows  slow  undulating  movements  of  the  ectoplasm  but  rarely 
protrudes  definite  pseudopodia.  In  Amoeba  Umax  (Fig.  12,  2),  which 
is  slug-like  in  form,  the  end  that  is  posterior  in  progression  shows 
a  fan -shaped  arrangement  of  short  ridges,  due  probably  to  the 

FIG.  12. 

Different  species  of  freshwater  Gymnamoebida.  1,  Dactylosphaera  radiosa,  x  260.  2, 
Amoeba  Umax,  x  200.  3,  Amoeba  verrucosa,  x  200.  4,  Amoeba  guttula,  Duj.,  regarded  as  a  young 
form  of  A.  proteus  by  Leidy.  5,  Amoeba  proteus.  6,  Amoeba  (Ouramoeba)  vorax,  x  130.  N, 
nucleus  ;  c.v,  contractile  vacuole  ;  F.v,  food  vacuole  ;  F,  hyphae  of  a  fungus.  In  Amoeba  vorax 
some  of  the  large  diatoms  (D,  D)  upon  which  it  feeds  and  the  approximate  positions  of  the 
nucleus  and  contractile  vacuole  are  shown.  (1,  2,  3  from  Cash ;  4,  5,  6  from  Leidy.) 

wrinkling  of  the  surface  in  the  vortex  of  the  retreating  axial  stream 
.{see  p.  69). 

The  marine  Amoebae  have  not  yet  been  carefully  recorded. 
Amoeba  crystalligera  is  often  found  in  marine  aquaria,  and  a  species 
allied  to  the  freshwater  A.  guttula  has  been  found  at  Woods  Hole 
in  America.  Amoeba  fluida  was  found  in  sea- water  aquaria  in 
Freiburg  by  Gruber,  and  this  with  two  other  species  were  also 
found  by  him  in  the  Gulf  of  Genoa. 


It  may  be  regarded  as  extremely  doubtful  whether  the  forms 
that  the  Amoebae  present  really  indicate  true  differentiation  into 
definite  species,  or  represent  the  varying  influence  of  certain  ex- 
ternal conditions  acting  upon  one  species,  or,  again,  represent 
different  phases  in  the  life  -  history  of  one  or  more  distinct 
species.  Thus  it  has  been  observed  that  when  the  amoebae 
found  on  the  surface  of  decomposing  hay  infusions  are  placed  upon 
a  slide,  broad  lobate  pseudopodia  begin  gradually  to  be  extended 
in  various  directions  and  the  general  form  of  Amoeba,  proteus  is 
assumed.  After  a  time,  when  progression  may  be  induced  in  one 
direction,  the  body  becomes  elongated  and  more  or  less  pointed  at 
the  anterior  end,  so  that  the  form  becomes  similar  to  that  known 
as  A.  Umax.  If  the  water  be  made  very  feebly  alkaline  the  amoebae 
contract  into  a  spherical  shape  with  very  short  dentate  pseudopodia, 
similar  to  A.  guttula,  and  then  protrude  long  pointed  pseudopodia 
similar  to  those  of  Dadijlosphaera  radiosa.1 

The  forms  usually  attributed  to  the  genus  Ouramoeba,  Leidy, 
have  been  shown  to  be  Amoebae  in  which  fungal  filaments  are 
growing  (Poteat  [21]).  The  filaments  arise  from  spores  which  are 
always  situated  in  the  neighbourhood  of  the  contractile  vacuole.  It 
has  been  suggested  that  the  fungus  receives  nourishment  from  the 
waste  products  of  the  amoeba.  These  filaments  have  been  observed 
in  Amoebae  attributed  to  the  species  A.  villosa,  A.  linucleata,  and 
A.  proteus. 

The  life -history  of  no  species  of  Amoeba  has  yet  been  fully 
worked  out,  but  Calkins  (7)  has  shown  that  Amoeba  proteus 
normally  passes  through  an  early  stage  when  the  pseudopodia  are 
relatively  long  and  more  pointed  and  similar  to  those  of  A.  radiosa ; 
and  Scheel  (29)  has  proved  that  the  uninucleate  condition  is 
succeeded  by  a  multinucleate  condition  previous  to  encystment. 

Calkins  suggests  that  the  life-cycle  of  Amoeba  proteus  may  be 
somewhat  as  follows : — The  zygote  gives  rise  to  a  small  radiate 
form,  which  develops  into  the  uninucleate  type-form.  This 
encysts  and  by  schizogony  gives  rise  to  uninucleate  Amoebae, 
which  develop  into  the  multinucleate  type-form.  The  multi- 
nucleate  type-form  encysts  and  gives  rise  to  the  gametes,  which 
conjugate  to  form  the  zygotes. 

Paramoeba,  Schaudinn.  Several  radiating  pseudopodia.  A  well- 
defined  chromatin  body  is  present  in  tlie  cytoplasm  close  to  the  nucleus. 
Swarm-spores  with  two  flagella.  P.  eilhardi  was  found  in  a  marine 
aquarium  in  Berlin.  10-90  /JL.  P.  hominis,  a  human  parasite  (p.  83). 

Dactylosphaera,  Hertwig  and  Lesser  (Fig.  12,  1),  is  distinguished  from 
Amoeba  by  the  numerous  rigid  pseudopodia,  \vliich  do  not  completely 
retract  when  at  rest.  Freshwater.  Maximum  120  /*. 

1  Verworn,  General  Physiology,  English  translation,  1899,  p.  184  ;  and  Dofleii), 
F.,  Archiv  Prot.  Suppl.,  1907,  p.  250. 



Lithamoeba,  Lankester1  (Fig.  13).  Body  discoid,  pseudopodia  lobular 
and  hernia-like.  A  distinct  pellicle  covering  the  body,  which  ruptures 
for  the  protrusion  of  the  pseudopodia.  Freshwater.  Maximum  125  p. 

Dinamoeba,  Leidy.  Pseudopodia  long,  conical,  and  acute.  Body 
enveloped  in  a  delicate  hyaline  jelly  bristling  with  minute  spicules. 
Bogs  of  New  Jersey.  60-160  /A. 

The  following  genera  were  described  by  Frenzel  (8,  9)  from  fresh 
water  in  the  Argentine  Republic :  Chromatella,  Stylamoeba,  Saltonella, 
and  Eikenia. 

Centrochlamys,  Claparede  and  Lachmaun.  The  body  covered  with  a 
thin,  membranous,  disc-shaped  test  through  which  the  pseudopodia  pro- 

Fio.  13. 

Liihamoeba  diseus,  Lank.  A,  quiescent;  B,  throwing  out  pseudopodia.  c.?',  contractile 
vacuole,  overlying  which  the  vacuolated  protoplasm  is  seen ;  cone,  concretions  insoluble  in 
dilute  HC1  and  dilute  KHO,  but  soluble  in  strong  HC1 ;  /,  food  particles  ;  n,  nucleus.  (After 

trude.  No  definite  pylome.  A  single  nucleus  and  several  contractile 
vacuoles.  Freshwater.  40-45  p.. 

Amphizonella,  Greeff.  Probably  closely  related  to  Centrochlamys.  The 
body  is  usually  invested  by  a  supple  membrane  which,  under  some  circum- 
stances, is  itself  surrounded  by  a  transparent  mucilaginous  envelope. 
The  pseudopodia  are  pushed  through  these  membranes  and  withdrawn 
again  without  leaving  any  definite  aperture.  It  has  not  been  deter- 
mined whether  the  position  on  the  test  through  which  the  pseudopodia 
protrude  is  definitely  fixed  or  varies.  These  two  last-named  genera 
are  undoubtedly  closely  allied  to  Corycia,  Cochliopodium,  and  other 

Hyalodiscus,  Hertwig  and  Lesser.  The  ectoplasm  usually  very  thick, 
and  sometimes  exhibiting  radiating  lines.  A  creeping  movement  with- 
out pseudopodia  frequently  occurs.  One  or  more  inconspicuous  nuclei. 
Freshwater.  40-60  //,. 

Trichosphaerium,  Schneider.  The  structure  and  life-history  of  this 
genus  has  been  fully  described  by  Schaudinn  (26).  The  body  is  in- 
vested by  a  gelatinous  test  perforated  by  many  pores  for  the  protrusion 

1  Lankester,  Q.  J.  Micr.  Sci.  xix.,  1879,  p.  484. 



of  long  digitate  pseudopodia ;  several  nuclei ;  no  contractile  vacuoles. 
Zooxanthellae  occur  in  the  protoplasm.  Marina 

Pelomyxa,  Greeff.  A  remarkable  genus  of  Gymnamoebida  found  in 
the  mud  of  ponds  and  ditches,  and  distinguished  by  the  presence  of  an 
enormous  number  of  minute  nuclei.  Several  species  have  been  described. 
P.  palustris,  Greeff,  P.  villosa,  Leidy, 
are  frequently  found  in  this  country 
and  are  probably  cosmopolitan.  P. 
penardi,  Rhumbler  (22),  was  found 
at  Gottingen.  P.  viridis  has  only 
been  found  in  British  India. 

They  vary  considerably  in  size, 
but  when  spread  out  in  progression 
P.  viridis  may  attain  to  a  size  of  8 
mm.  in  diameter,  and  the  other 
species  to  2  mm. 

The  form  of  the  animal  is  like 
that  of  an  amoeba,  and  progress  is 
effected  by  means  of  numerous 
blunt  lobose,  villiform,  or  some- 
times attenuate  and  anastomosing 
pseudopodia  of  very  variable  form 
and  length.  There  is  neither  test  FIG.  14. 

nor  enveloping  membrane.  Pelomyxa   palustris,   Greeff.     An   example 

T       ,  .  with  comparatively  few  food  particles.    (After 

In  the  ordinary  vegetative  con-   Qreeff.) 

dition  of  Pelomyxa  there  are  very 

many  nuclei.  Bourne  (3)  calculated  that  in  a  large  specimen  of  P.  viridis 
there  may  be  10,000  nuclei.  In  addition  to  the  nuclei  there  are  numerous 
minute  scattered  chromidia  (Bott  [2])  (Fig.  7).  These  chromidia  may  be 
clearly  seen  in  the  ectoplasm.  The  chromidia  are  formed  by  the  chromatin 
discharged  from  the  nuclei,  and  they  never  unite  to  form  a  chromidial 
network.  In  addition  to  the  nuclei  and  chromidia,  the  cytoplasm  contains 
refringent  bodies  of  a  proteid  nature  (Veley  [34]),  numerous  symbiotic 
bacteria,  food  -  vacuoles,  and  various  water  -  vacuoles,  and  minute 

The  refringent  bodies  appear  to  be  waste  materials  and  probably  a 
by-product  of  metabolism,  and  are  undoubtedly  used  as  the  food  material 
of  the  symbiotic  bacteria.  They  are  sometimes  ejected  from  the  body, 
but  in  general  the  Pelomyxa  relies  on  the  bacteria  as  scavengers  to 
clear  its  protoplasm  of  these  bodies.  The  life-history  of  the  symbiotic 
bacteria  (Oladothrix  pelomyxae)  has  been  studied  by  Veley,  who  also 
determined  the  proteid  nature  of  the  refringent  bodies  by  obtaining  the 
characteristic  reactions  with — (1)  Millon's  reagent ;  (2)  sugar  and  sul- 
phuric acid  ;  (3)  the  xanthoproteic  test ;  and  (4)  with  caustic  soda  and 
copper  sulphate. 

The  green  vesicles  described  by  Bourne  in  P.  viridis  appear  to  be  of 
the  same  nature  as  the  refringent  bodies,  but  stained  with  chlorophyll 

The  protoplasm  of  all  the  species  contains  a  number  of  vacuoles  and 
vesicles,  but  none  of  them  appear  to  be  rhythmically  contractile. 

82  THE  LOB  OS  A 

Endamoeba}- — 'The  species  of  this  genus  are  parasitic  in  the 
intestines  of  various  animals.  There  is  no  contractile  vacuole,  and 
rarely  more  than  one  short  pseud opodium  is  protruded.  Endamoeba 
coli  is  commonly  found  in  the  human  intestine.  It  is  often  present 
in  perfectly  normal  health,  and  is  not  associated  with  or  the  cause 
of  disease.  The  size  does  not  exceed  50  p. 

Endamoeba  histolytica  is  so  similar  in  size  and  form  to  E.  coli 
in  some  stages  of  its  life-history  that  it  has  been  regarded  as  the 
same  species,  but  it  is  now  known  to  have  a  different  life -history 

and  to  be  the  active  cause  of  certain 
'":::N  forms  of  tropical  dysentery.  It  is 
found  not  only  in  the  ulcers  of  the 
intestinal  mucous  membrane,  but 
also  in  abscesses  of  the  liver  accom- 
panying the  disease.  It  penetrates 
the  mucous  membrane  of  the  intes- 
tine and  enters  the  submucosa 
(Dopter  [42]). 
FIO.  15.  The  life -history  of  Endamoeba 

Endamoeba  coli.    A,  a  specimen  with  one  7)7e//i7<>;/?V/7    TIQO  «r>f  Traf    V>PPTI    -fnllv 

nucleus  in  the  resting   condition.     B,-  a  ntStOtyttCa    Has  not  yet    t 

specimen  with  two  nuclei.     (After  Casa-  worked     OUt.  It  is    very    Similar 

grandi  and  Barbagallo.)  .  n        T 

in  size  and  appearance  to  L.  con, 

but  differs  from  it  in  the  somewhat  indefinite  and  variable 
character  of  having  usually  a  more  distinct  hyaline  ectoplasm. 
According  to  Lesage  (43)  the  large  cysts,  similar  to  those  of  E.  coli, 
20  ju,  in  diameter,  are  never  found  in  this  species.  In  E.  histolytica 
the  cysts  are  3-6  //,  in  diameter.  During  the  progress  of  the  disease 
which  it  causes  it  is  constantly  changing  its  shape  and  position,  and 
asexual  reproduction  proceeds  rapidly  by  simple  fission  or  multiple 
gemmation.  Cyst-formation  only  begins  when  healing  commences, 
never  in  the  height  of  the  disease.  The  encystment  is  preceded 
by  the  rapid  discharge  of  chromidia  into  the  cytoplasm,  and  then 
the  nucleus  degenerates  and  disappears.  The  chromidia  then  collect 
to  form  a  chromidial  network  in  the  ectoplasm,  and  subsequently 
spherical  bodies,  the  cysts,  each  surrounded  by  a  yellowish-brown 
membrane  and  containing  a  portion  of  the  chromidial  network,  are 
pinched  off  (Fig.  1 6,  D).  The  rest  of  the  life-history  has  not  been 
followed,  but  it  has  been  shown  that  when  the  cysts  are  given  to 
cats  they  cause  a  dysenteric  disease. 

Other  species  of  Endamoeba  have  been  described  from  the  human 
intestines,  but  it  is  uncertain  at  present  whether  they  are  or  are 

1  The  account  given  of  Endamoeba  coli  and  E.  histolytica  is  mainly  taken  from 
the  important  memoir  of  Schaudinn.  This  memoir  is,  however,  not  illustrated. 
For  further  information  and  for  figures  of  Endamoeba  coli  the  reader  is  referred 
to  the  memoir  by  Casagrandi  and  Barbagallo  (38),  and  of  E.  histolytica  to  the 
memoir  of  Jiirgens  (39)  and  other  papers  mentioned  in  the  list  of  literature  on 
p.  92. 


not  associated  with  disease.  Endamoeba  undulans,  Castellani  (40), 
exhibits  a  peculiar  amoeboid  form,  which  occasionally  protrudes  a 
single  pseudopodium.  There  is  practically  no  distinction  between 
the  ectoplasm  and  endoplasm.  The  presence  of  a  peculiar  undulat- 
ing membrane  running  round  one  end  of  the  body  suggests  that 
the  species  may  have  different  affinities  to  the  ordinary  species  of 
Endamoeba.  25-30  //,.  Ceylon.  Endamoeba  iurai,  Ijima  (12),  has 
been  described  from  the  human  intestines  in  Japan. 

The  species  described  under  the  name  Parainoeba  hominis  by 
Craig  (41)  was  found    in    the    faeces    of   patients  suffering   from 


Fio.  16. 

KiK/'Uiioeba  histolytica,  Schaudinn.  A,  B,  two  specimens  from  a  case  of  dysentery  in  a  cat ; 
c,  blood  corpuscles  being  digested  ;  N,  nucleus.  (After  Jiirgens.)  C,  specimen  from  human 
intestine  with  resting  nucleus  (N)  and  a  single  non-contractile  vacuole.  D,  specimen  giving 
rise  by  gemmation  to  a  spore  ;  eh,  chromatin  of  nucleus  in  the  form  of  scattered  chromidia  ; 
sp,  protoplasm  of  spore  containing  some  chromidia.  (C  and  D  after  Lesage.) 

severe  diarrhoea  in  the  Philippine  Islands,  associated  with  E. 
histolytica  and  other  Protozoa.  There  appear  to  be  three  phases  in 
the  life  -  history  :  (1)  an  amoeboid  phase,  15-25  p.;  (2)  a  resting 
cystic  stage,  15-20  //,;  (3)  a  biflagellate  phase,  3-15/z.  Notwith- 
standing the  general  resemblance  in  its  life-history  to  that  of  the 
marine  Paramoeba  eilhardi,  it  is  difficult  to  believe  that  this  species 
is  rightly  placed  in  the  same  genus. 

Endamoeba  blattae  is  often  found  in  the  rectum  of  the  common 
cockroach.  In  form  it  is  similar  to  Amoeba  Umax,  but  it  seldom 
pushes  out  a  single  pseudopodium  and  has  remarkably  clear  proto- 
plasm. It  may  be  as  much  as  80  //,  in  diameter.  Other  species 
probably  belonging  to  the  same  genus  are  found  in  the  intestines 
.of  mice  and  in  the  rectum  of  the  frog. 



It  is  difficult  to  determine  at  present  the  true  nature  of  many 
of  the  amoeboid  cells  found  in  the  pus  and  other  fluids  of  patho- 
logical conditions,  but  the  following  are  regarded  as  parasitic 
organisms  :  Amoeba  urogenitalis,  Amoeba  kartulisi, 
Amoeba  buccalis. 

Leydenia  gemmipara  is  an  amoeboid  cell  originally 
found  by  Lieberkiihn  in  the  ascites  fluid  of  malignant 
tumours.  The  endoplasm  contains  numerous  fat 
spherules,  remnants  of  red  and  white  corpuscles,  and 
numerous  crystalline  bodies.  The  most  remarkable 
feature  of  Leydenia,  however,  is  the  presence  of  a 
definite  contractile  vacuole.  Plastogamy  frequently 
occurs,  and  reproduction  is  effected  by  fission  and 
gemmation.  There  seems  to  be  little  doubt  from 
the  researches  of  Schaudinn  that  Leydenia  is  an  in- 
dependent  organism,  but  whether  it  should  be  placed 
with  tne  LoDOsa  or  with  the  Myxomycetes  is  not 


teria;  c,  at  the  an- 
terior  pole  granules 
are  seen  arranged  in 
the  direction  of  the 
protoplasmic  cur- 

rents   (After  schu- 


The  body  is  protected  by  a  shell  or  test,  which 
may  be  perforated  by  a  hole  —  the  pylome  —  or 
widely  open  on  one  side  like  a  cap.  The  test  is  not  perforated  by 
the  pseudopodia. 

The  test  of  the  Thecamoebida  is  composed  of  two  sheaths  — 
an  inner  sheath,  which  is  in  the  form  of  a  thin  continuous  layer  ; 
and  an  outer  sheath,  which  is  usually  much  thicker,  and  may  be 
strengthened  by  the  secretion  of  definite  hard  plates  or  by  the 
adhesion  of  foreign  materials  of  various  kinds.  The  chemical 
constitution  of  the  test  is  difficult  to  determine  with  accuracy,  but 
it  appears  to  consist  of  an  organic  matrix  usually  containing  silica 
in  larger  or  smaller  proportions.  The  inner  sheath  of  the  test 
contains  a  small  proportion  or  only  traces  of  silica  ;  the  plates  and 
prisms  of  the  outer  sheath,  such  as  we  find  in  Quadrula  and  its 
allies,  contain  a  much  larger  proportion  of  silica.  The  matrix 
which  cements  the  plates  of  Quadrula  together,  and  which  fastens 
diatom  shells,  grains  of  sand,  and  other  foreign  bodies  to  the  test  of 
Difflugia,  is  an  organic  substance  which  also  contains  a  trace  of 
silica.  In  the  plates  of  Quadrula  irregularis  calcium  appears  to 
take  the  place  of  silicon. 

There  is  no  evidence  of  the  occurrence  of  chitin  in  the  tests  of 
any  Thecamoebida,  but  a  substance  allied  to  keratin  may  occur  in 
some  cases  (Awerinzew  [1]). 

In  the  Cochliopodiidae  the  shell  is  thin  and  flexible.  It  is 
usually  marked  by  minute  punctuations  arranged  in  definite  rows 
or  more  irregularly  distributed.  When  more  highly  magnified 


these  punctuations  appear  to  be  globular  in  shape,  but  their  precise 
nature  has  not  yet  been  determined. 

In  Quadrula  the  outer  sheath  consists  of  a  series  of  square 
plates  cemented  together  by  the  matrix.  These  plates  can  be 
raised  to  a  high  temperature  without  destruction  of  their  form. 
When  boiled  for  a  long  time  in  10  to  20  per  cent  KHO,  they 
are  dissolved  but  leave  behind  a  fine  granular  residue  which 
probably  represents  the  inorganic  components  of  the  plates.  In 
Nebela  the  plates  are  discoidal,  and  in  other  genera  irregular  in  form. 

The  diatom  or  desmid  shells,  the  grains  of  sand  or  glass,  and 
other  foreign  bodies  that  are  found  fastened  to  the  outer  sheath  of 
the  test  of  Difflugia  (Fig.  20)  and  its  allies  are  not  adventitiously 
placed,  but  are  caught  and  definitely  arranged  in  position  by  the 
animal  (Rhumbler).  There  can  be  little  doubt  that  Difflugia  exercises 
a  deliberate  choice  of  the  particles  it  uses  for  shell  purposes,  and 
to  a  certain  extent  the  character  of  the  foreign  particles  and  their 
arrangement  can  be  used  for  racial  or  specific  distinctions. 

In  the  Arcellidae  the  outer  sheath  is  composed  of  hexagonal  or 
irregular   prisms    (Fig.   1 8),   some    of   which,   situated  at  regular 
intervals,  are  rather  longer  than  the  others  and 
project  on  the  surface  as  round  knobs  or  bosses.       QcOnxcnnnmj 
The  prisms  are  cemented  together  by  an  extremely  FIG.  is. 

thin  matrix.  Section  through  the 

The  cytoplasm  of  the  Thecamoebida  is  often  BSSSttEB 
arranged  in  three  zones.  The  cytoplasm  of  the  som.e  of  ^hich  project 

,          , .  -i       i-      -i  •  r     i  i  .      -it  irregular    intervals 

pseudopodia  and  ot  the  region  of  the  pylome  is  as  shallow  bosses  on 
usually  remarkably  hyaline  and  the  granulations  AwerinUzew?)' 
extremely  fine.    In  the  middle  zone  it  is  more 
coarsely   granular,    and    contains   the    contractile    vacuoles,    food- 
vacuoles,  crystalline  bodies,  excreta,  oil-globules,  etc.     In  the  zone 
next  to  the  fundus  of  the  shell  is  usually  found  the  nucleus  or 
nuclei  and  the  sickle-shaped  or  more  irregularly  disposed  chromidial 
network.     In  the  Arcellidae,  however,  the  arrangement  is  somewhat 
different  from  this  (p.  86). 

The  pseudopodia  are  probably  subject  to  considerable  variation 
in  shape  and  number  according  to  external  conditions.  In  the 
Difflugiidae  there  may  be  only  one  long  finger-like  pseudopodium 
extended  to  a  length  double  that  of  the  shell,  or  there  may  be 
three  or  four  shorter  pseudopodia,  or  occasionally  as  many  as  seven 
protruded  at  the  same  time.  In  Heleopera  the  number  of  pseudo- 
podia appears  to  be  constantly  more  numerous  than  in  other  genera 
of  the  family. 

In  some  species  of  Arcellidae  and  Cochliopodiidae  a  membranous 
expansion  of  the  cytoplasm  sometimes  protrudes  from  the  pylome. 
Very  little  is  known  concerning  the  contractile  vacuoles  of  the 
Thecamoebida,  as  the  thick  opaque  test  interferes  considerably  with 


the  observation  of  it  in  the  living  animal,  but  it  seems  probable  that 
one  or  more  contractile  vacuoles  are  present  in  all  genera. 

Nucleus. — For  a  considerable  period  in  the  life-history  of  Arcella 
there  are  two  large  oval  nuclei,  from  0'015-0'02  mm.  in  diameter, 
which  are  usually  situated  some  distance  apart,  near  the  periphery 
of  the  cytoplasm.  More  rarely  three  or  even  four  of  these 
relatively  large  nuclei  may  be  found.  These  nuclei  are  derived  by 
the  karyokinetic  division  of  the  primary  single  nucleus  of  the  young 
Arcella.  Each  nucleus  contains  a  single  large  ("008  mm.)  nucleolus, 
which  apparently  consists  mainly  of  chromatin,  but  is  otherwise 
clear  and  transparent  (Fig.  21). 

In  other  Thecamoebida  (Diffiugia1  and  Centropyxis}  there  is 
usually  only  one  nucleus  during  the  corresponding  phase  of  the  life- 
history,  and  this  exhibits  a  coarse  reticulum  of  chromatin  with 
numerous  nucleoli  distributed  through  it. 

The  chromidial  network  of  Arcella  is  in  the  form  of  an 
irregular  band  or  ring  at  the  periphery  of  the  cytoplasm,  which 
sends  lobate  processes  or  branches  in  the  direction  of  the  central 
protoplasm.  These  processes  are  sometimes  pinched  off  from  the 
peripheral  ring,  and  appear  as  isolated  patches  of  the  chromidial 
network  in  the  central  cytoplasm. 

In  Centropyxis  the  chromidial  network  is  in  the  form  of  a  thick 
sickle-shaped  band  lying  in  contact  with  the  convex  aboral 
extremity  of  the  body.  Sometimes  this  band  envelops  the 
nucleus,  but  neither  in  Centropyxis  nor  in  Arcella  does  the  nucleus 
come  into  contact  with  the  network,  being  always  surrounded  by  a 
halo  of  clear  protoplasm  (Fig.  21).  In  some  forms  of  Difflugia 
the  chromidial  network  is  in  contact  with  the  nucleus  (Fig.  6) ; 
in  D.  globosa  and  others,  however,  there  is  a  clear  space  between  the 
nucleus  and  the  chromidial  network  as  in  Centropyxis,  but  in 
these  cases  strands  of  the  chromatin  seem  to  .connect  the  nucleus 
with  the  network. 

In  another  phase  of  the  life -history  of  Arcella  there  are 
numerous  nuclei.  The  number  is  very  variable,  from  5  to  39,  but 
in  a  great  many  cases  there  are  about  25.  These  secondary  nuclei 
are  formed  by  the  concentration  of  granules  of  chromatin  of  the 
chromidial  network,  which  become  rounded  off  and  surrounded  by 
a  nuclear  membrane.  The  larger  the  number  of  nuclei,  the  smaller 
they  are.  When  very  numerous  these  nuclei  are  not  more  than 
0'009-0-01  mm.  in  diameter.  As  the  secondary  nuclei  are  formed, 
the  two  or  three  primary  nuclei  degenerate  and  disappear. 

When  a  certain  number  of  secondary  nuclei  have  been  formed, 

they  divide  by  karyokinesis.    This  karyokinesis  is  a  preparation  for 

the  process  of  fission.     One  half  of  the  nuclei  resulting  from  the 

karyokinetic  division  remain  at  the  periphery,  the  remaining  half 

1  According  to  Zuelzer  there  are  10-30  nuclei  in  D.  urceolata,  Carter. 


migrate  towards  the  centre  of  the  protoplasm.  It  is  probably  this 
central  party  of  nuclei  that,  with  their  surrounding  protoplasm, 
protrude  from  the  pylome  of  the  shell  and  give  rise  to  the  daughter 
Arcella  in  the  process  of  fission.1 

In  Centropyxis  (Schaudinn  [27])  the  formation  of  secondary 
nuclei  previous  to  fission  does  not  occur.  When  fission  is  about  to 
take  place,  a  considerable  portion  of  the  protoplasm  protrudes  from 
the  pylome,  assumes  the  inverted  form  of  the  parent,  and  develops  a 
shell.  The  nucleus  remains  in  that  part  of  the  protoplasm  which 
at  this  stage  only  half  fills  the  shell  of  the  parent  Centropyxis.  When 
the  daughter  shell  is  formed  the  nucleus  increases  to  nearly  double 
its  former  size,  the  nucleolus  dwindles  in  size,  and  numerous  minute 
chromosomes  are  formed.  These  changes  are  followed  by  the 
formation  of  a  spindle,  the  arrangement  of  the  chromosomes  in  an 
equatorial  plate,  and  subsequently  by  nuclear  division.  One  of  the 
nuclei  thus  formed  passes  into  the  daughter  individual  and  the  other 
remains  in  the  parent. 

While  these  changes  in  the  nucleus  are  taking  place,  the 
chromidial  network  divides  into  a  great  number  of  chromidia,  which 
collect  round  the  two  nuclei  in  equal  proportions  and  pass  with 
them  into  the  resultant  individuals. 

Encystment. — The  formation  of  resting  cysts  occurs  in  Arcella, 
Centropyxis,  Nebela,  Diffluyia,  and  probably  in  all  the  other 
Thecamoebida  (Martini  [16]). 

In  Centropyxis,  Schaudinn  found  that  cj'sts  are  formed  when 
external  conditions  are  unfavourable,  such  as  in  cases  of  desiccation, 
scarcity  of  food,  etc.  In  such  cases  the  food  particles,  diatom 
shells,  excreta,  a  considerable  proportion  of  the  water,  and  any  other 
non-essential  contents  of  the  protoplasm,  are  ejected,  while  the 
cytoplasm,  with  the  contained  chromidial  network  and  nucleus, 
contracts  into  a  ball  and  is  surrounded  by  a  cyst- wall. 

At  the  end  of  encystment  the  cyst  -  wall  disintegrates,  the 
protoplasm  swells  up  to  its  former  size,  and  the  normal  processes 
of  life  are  continued.  It  does  not  seem  probable  in  this  case 
that  encystment  has  any  connexion  whatever  with  the  sexual 

In  Arcella,  however,  according  to  Hertwig  (11),  a  reduction 
in  the  number  of  the  nuclei  takes  place,  and  it  is  suggested  that 
the  process  of  conjugation  may  occur  during  this  period  of  encyst- 
ment, in  a  manner  similar  to  that  which  occurs  in  Actinosphaerium.1 

In  Difflugia  urceolata  (Zuelzer  [35])  a  process  of  encystment  occurs 
in  the  late  autumn,  and  is  accompanied  by  a  destruction  of  a  great 
many  of  the  old  nuclei.  Before  the  cysts  rupture  in  the  spring  the 
contents  break  up  into  a  number  of  uninucleate  secondary  cysts, 
but  the  history  of  the  secondary  cysts  has  not  been  followed. 

1  See  Note,  p.  93. 


Plastogamy. — A  process  of  the  temporary  or  permanent  fusion 
of  two  or  more  individuals  has  been  observed  by  Schaudinn  (27) 
in  Centropyxis,  and  by  Zuelzer  (35)  in  Diffiugia.  urceolata,  and  probably 
occurs  in  other  Thecamoebida.  In  Centropyxis  two  individuals  may 
join  together  plastogamically  and  produce  a  daughter  individual 
with  two  nuclei  and  two  chromidial  networks,  or  if  three  individuals 
join  together  they  produce  a  daughter  individual  with  three  nuclei 
and  three  chromidial  networks.  In  some  cases,  the  daughter 
individual  produced  by  the  plastogamy  has  an  abnormal  shell  and 
the  two  nuclei  and  chromidial  networks  fuse  together.  In  other 
cases,  again,  only  one  of  the  individuals  gives  rise  to  a  daughter 
individual,  and  that  is  of  the  normal  type. 

In  Difflugia  urceolata  a  process  of  plastogamy  occurs  in  which  the 
nuclei  and  chromidial  networks  remain  passive,  when  external  con- 
ditions become  unfavourable,  but  this  appears  to  be  antecedent  only 
to  disintegration.  In  the  autumn,  however,  the  protoplasm  of  one 
of  the  two  participants  in  a  plastogamic  union  passes  into  the  shell 
of  the  other,  and  more  rarely  a  process  of  plastogamy  occurs  in  which 
the  nuclei  and  chromidial  network  of  both  individuals  are  active,  but 
definite  fusion  of  nuclear  elements  has  not  been  observed.  At  the 
end  of  this  plastogamic  fusion  the  empty  shell  may  become  firmly 
fixed  to  the  shell  containing  the  fused  individuals,  giving  rise  to 
the  twin- shells  so  often  found  in  cultures  of  these  creatures 
(Rhumbler  [22]).  The  meaning  of  the  different  forms  of  plasto- 
gamy in  the  Thecamoebida  is  not  clear,  but  there  is  no  evidence  at 
present  that  they  represent  any  phase  of  the  true  sexual  process. 

The  only  observation  of  a  true  conjugation  in  the  order  is  that 

described  by  Schaudinn,  in  which 
definite  heterogametes  are  formed 
and  conjugate  (p.  77).1 

— -a, 

usually  thin  and  supple,  with  a 
flexible  margin,  shaped  like  a  cap, 
limpet  shell,  or  helmet.  Pylome 
widely  open. 

The  genera  included  in  this  family 
have  close  affinities  with  some  of  the 
Gymnamoebida.  The  shell  is  not 
perforated  by  the  pseudopodia,  but  in 
Cochliopodium  it  often  assumes  many 
CoMiopodiun  pellutidum,  Hert.  and  different  shapes  according  to  the 

Less,    a,  nucleus,  surrounded  by  a  halo  of  conditions  of  the  animal,  and  in  some 

species  usually  attributed  to  the  genus 
(G.   adinophorum  and  G.   digitatum)  it 

entirely  surrounds  the  body  and  is  perforated  by  the  pseudopodia,  the 

1  See  Note,,  p.  93. 

Fia.  19. 




apertures  being  closed  again  when  the  pseudopodia  are  withdrawn. 
Cochliopodium,  Hert.  and  Less.,  then,  is  the  connecting-link  between  the 
two  orders.  In  Corycia,  Dujardin,  the  test  is  supple  and  membranous,  but 
the  pylome  remains  open.  In  Pseudochlamys,  Clap,  and  Lach.,  the  shell  is 
shaped  like  that  of  a  limpet,  but  is  very  flexible,  and  the  margin  of  the 
pylome  may  in  the  retracted  condition  be  inflected  to  form  a  shelf  like 
the  velum  of  a  medusa.  In 
Parmulina,  Penard,  the  test  is 
in  the  shape  of  a  cup  or  bowl. 
In  Hyalosphenia,  Stein,  the  test 
is  rigid  except  at  its  margin. 

Tests  usually  globular,  or  flask - 
ehaped  with  a  narrow  pylome. 
Outer  sheath  of  the  test  with 
hard  plates,  or  with  adherent 
foreign  particles,  or  with  both. 

Dijfluyia,  Leclerc,  is  a  genus 
which  exhibits  a  great  many 
varieties  of  form,  some  of  which 
are  very  common.  The  shell 
is  usually  flask  -  shaped,  and 
consists  of  a  tough  double 
membrane  to  which  various 
foreign  bodies,  such  as  diatom 
shells,  sponge  spicules,  sand- 
grains,  etc.,  are  cemented.  The 
pseudopodia  are  rarely  more 
than  two  or  three  in  number, 
digitiform  and  blunt,  but  some- 
times frayed  at  the  extremities. 
Some  of  the  larger  varieties  are 
over  0'5  mm.  in  length. 

Centropyxis,  Stein  (  =  Echi- 
nopyxis,  Clap,  and  Lach.),  is 

related    to    Difflugia,    but    the         \J  FIG.  20. 

Bhell    is     usually    discoidal     Or         Aj  Diffiu{,ia  pyrifwmis,  Perty,  with  very  large 
oval,  With  the  pvlome  excentric    diatom    shells  attached  to  the  theca.    B,  test  of 
.   .  r  _        .  Quadrula    symmetrica,     Wallich.       C,     Lecquermsia 

in     position.         It     IS      covered    spiralis,  Ehr.      D,  diagram  of  test  of  Pontigulasia 

irre^ularlv    with     forpitm    mr     irlcisa>  Rhumbler,  showing  the  collar  (co)  and  bridge 
reign    par-  (b)    E)  vjew  of  the  bridge  (6)  of  Pmitiguiasia  from 

tides,    and    sometimes    exhibits    above.    (A-C  after  Leidy  ;  D,  B  after  Penard.) 
two  or  three  short  spines. 

Pontigulasia,  Rhumbler,  and  Cucurbitella,  Penard,  are  distinguished 
by  the  presence  of  a  short  collarette  round  the  pylome.  In  Pontigulasia 
(Fig.  20,  D  and  E)  a  broad  flat  bridge  runs  across  the  base  of  this  collarette 
and  divides  the  pylome  into  two  apertures.  In  Lecquemisia,  Schlumberger 
(Fig.  20,  C),  the  shell  is  cornuate  or  slightly  spirally  twisted.  The  genera 
Quadrula,  Nebela,  and  Heleopera  form  shells  with  siliceous  plates  and  are 
not  usually  decorated  at  all  with  foreign  particles.  Quadrula,  F.  E. 

90  THE  LOB  OS  A 

Schultze,  is  a  common  and  widely  distributed  genus,  with  a  shell  of  vari- 
able shape,  but  distinguished  by  its  regular  pavement -like  arrangement 
of  square  or  oblong  plates  (Fig.  20,  B).  Nebela,  Leidy,  is  related  to 
Quadrula,  but  the  plates  of  the  shell  are  round,  oval,  or  even  irregular  in 
outline.  In  some  species  the  shell  is  strengthened  by  adherent  diatom 
shells.  In  all  species  of  this  genus  particles  of  "fat"  of  a  pale  blue  or 
yellow  colour  occur  normally  in  the  protoplasm.  Similar  particles  also 
occur  in  Difflugia  and  other  genera,  but  are  not  so  constant  or  characteristic 
as  they  are  in  Nebela. 

The  shell  of  Heleopera,  Leidy,  is  provided  with  square  or  oblong 
plates  as  in  Quadrula,  but  they  are  usually  irregularly  or  untidily 
arranged.  The  pseudopodia  of  this  genus  are  more  numerous  than  in 
the  others  of  the  family,  and  are  sometimes  slightly  branched. 

In  Phryganella,  Penard,  the  shell  is  covered  with  adventitious  particles, 
as  in  Difflugia,  but  the  pseudopodia  are  more  numerous,  more  delicate, 
frequently  branched,  and  occasionally  amalgamated  at  the  base  to  form  a- 
membranous  web.  It  appears  to  be  related  to  Pseudodifflugia,  Schlum- 
berger,  which  is  usually  regarded  as  a  member  of  the  Order  Gromiidear 
of  the  Foraminifera.  As  it  is  quite  impossible  to  draw  a  definite  line  of 
distinction  between  organisms  with  a  few  fine  blunt  pseudopodia  such  as 
are  characteristic  of  the  Difflugiidae  and  those  with  filamentous  branching 
pseudopodia  such  as  are  characteristic  of  the  Gromiidea,  there  is  a  group 
of  genera  occupying  an  intermediate  position  between  the  Rhizopoda  and 
the  Foraminifera. 

The  principal  genera  of  this  group  are  : 

Cryptodifflugia,  Penard ;  Pseudodifflugia,1  Schlumb. ;  Diaphwodon,^ 
Archer ;  Platoum,1  F.  E.  Schultze ;  Clypeolina,  Penard ;  Nadinella,  Penard; 
Frenzelina,  Penard  ;  Campascus,1  Leidy  ;  Cyphoderia,1  Schlumb. 

Family  ARCELLIDAE.  Shells  plano-convex  in  shape,  marked  by  a 
very  fine  hexagonal  pattern,  not  supported 
by  adventitious  particles. 

Arcella,  Ehr.  This  is  a  common  and 
widely  distributed  gemis.  The  shells  of 
the  common  species  A.  vulgaris  vary  from 
80-140  p.  in  diameter,  and  like  those  v of 
most  of  the  species  of  Arcella  are  charac- 
terised by  their  brown  colour.  The  flattened 
side  of  the  shell  is  usually  depressed  and 
perforated  at  the  centre  by  the  pylome, 
FIO.  21.  which  is  less  than  one-third  the  diameter 

Arcella  vulgaris,  Ehr.    a,  shell ;  of    the    shell.        From    the    pylome    there 
b,  protoplasm  within  the  shell ;  c,  .    ,-,  f  •,     '  j •    • ,    , 

lobose  pseudopodia ;  e,  one  of  the  project  three  or  four,  rarely  more,  digitate 

marginal  vacuoles ;  d,  d,  nuclei  sur-  pseudopodia.     Situated   in    the    ectoplasm, 

•  rounded  by  a  halo  of  clear  proto-  x  .  .     .  ,      . 

plasm.    (After  Lankester.)  and  usually  arranged  in  a  circle  round  the 

pylome,    there    is    often    seen    a    series    of 

vacuoles,  which  probably  serve  a  hydrostatic  function.  They  may  fuse 
together  to  form  a  single  large  excentric  vacuole,  and  this  may  collapse 
after  the  manner  of  a  contractile  vacuole. 

1  Cf.  Treatise  on  Zoology,  Part  I.  Fasc.  II.  pp.  140-141. 

THE  LOB  OS  A  91 

Arcella  is  common  in  bogs  and  stagnant  water,  but  is  occasionally 
found  in  clear  running  water. 

Pyxidicula,  Ehr.,  differs  from  Arcella  in  having  a  large  gaping  pylome. 
The  surface  of  the  shell  is  ornamented  with  numerous  minute  tubercles. 
20-50  /*.  The  genus  is  comparatively  rare  and  little  known. 


1.  Awerinzcw,   S.      Die   Structur  und  die  chemische  Zusammensetzung  der 

Gehause  bei  den  Stisswasserrhizopoden.     Arch.  Prot.  viii.,  1906,  p.  95. 

2.  Bott,  K.     Ueber  die  Fortpflanzung  von  Pclomyxa  palustris.     Arch.  Prot. 

viii.,  1906,  p.  120. 

3.  Bourne,  A.  (r.     On  Pelomyxa  viridis  n.  sp.     Q.  J.  Micr.  Sci.  xxxii.,  1891, 

p.  357. 

4.  Butschli,    0.      Investigations   on  Microscopic  Foams   and   on  Protoplasm. 

Translated  by  E.  A.  Miiichin.     Black,  1894. 

5.  Untersuclmngen  liber  Structure!!.     1898. 

6.  Calkins,  G.  N.     Marine  Protozoa  from  "Woods  Hole.     U.S.  Fish.  Comm. 

Bull.  1901,  p.  413. 

7.  Evidences  of  a  Sexual  Cycle  in  the  Life-History  of  Amoeba  proteus. 

Arch.  Prot.  v.,  1904,  p.  1. 

8.  Frenzel,  J.     Untersuchungen  iiber  die  mikroskopische  Fauna  Argentiniens. 

Arch.  mikr.  Anat.  xxxviii.,  1891,  p.  1. 

9.  U^ber  einige  merkwiirdige  Protozoen  Argentiniens.     Zeitschr.  wiss. 

Zool.  liii.,  1892,  p.  334. 

10.  Goldschmidt,  R.      Die  Chromidien  bei  Protozoen.     Arch.   Prot.   v.,  1904, 

p.  126. 

11.  Hertwig,  R.    Ueber  Encystirung  und  Kernvermehrung  bei  Arcella  vulgaris. 

Fest.  Kupffer,  1899. 

12.  Ij-ima.     New  Rhizopod  of  Man.     Annot.  Zool.  Jap.  1898,  p.  85. 

13.  Jennings,  If.  S.      Contributions  to  the  Study  of  the   Behaviour  of   the 

Lower  Organisms.     Washington,  1904. 

14.  The  Movements  and  Reactions  of  Amoeba.     Biol.  Centralbl.  xxv., 

1905,  p.  92. 

15.  Lei/den,  E.,  and  Schaudinn,  F.    Leydenia  gemmipara.     S.-B.  Akad.  Berlin, 

vi.,  1896. 

16.  Martini.   N.     Beobaclitungcn  an  Arcella  vulgaris.      Zeitschr.   wiss.  Zool. 

Ixxix.,  1905,  p.  574. 

17.  Mesnil,  Felix.     Chromidies  et  questions  connexes.     Bull.   Inst.   Pasteur, 

iii.,  1905,  p.  313. 

18.  Neresheimer,  E.     Ueber  vegetative  Kernveranderungen  bei  Amoeba.    Arch. 

Prot.  vi.,  1905,  p.  147. 

19.  Penard,  E.     Faune  rhizopodique  du  bassin  de  Leman.     1902. 
20. Amibes  a  pellicule.     Arch.  Prot.  vi.,  1905,  p.  296. 

21.  Potent,  W.     Leidy's  genus  Ouramoeba.     Science,  viii.,  1898,  p.  778. 

22.  Rhumbler,  L.     Beitrage  zur  Kenntniss  der  Rhizopoden.      Zeitschr.  wiss. 

Zool.  Hi.,  1891  ;  and  same  journal,  Ixi.,  1896. 

23.  Zur  Theorie  der  Oberflacheiikriifte  der  Amoeben.     Zeitschr.  wiss. 

Zool.  Ixxxiii.,  1905,  p.  1. 


24.  Schaudinn,  F.     Ueber  die  Theilung  von  Amoeba  binucleata.     S.-B.  Ges. 

Naturf.  Berlin,  1895,  p.  130. 

25.  Ueber   den   Zeugungskreis   von  Paramocba  eilhardi.      S.-B.    Ak. 

Berlin,  1896,  p.  31. 

26.  Untersuchungen  iiber  den  Generationswechsel  von  Trichosphaerium 

sieboldi.     Anhang  z.  d.  Abh.  Ak.  Berlin,  1899. 

27.  Untersuchungen  iiber  die  Fortpflanzung  einiger  Rhizopoden.     Arb. 

kais.  Gesundheitsamte,  xix.,  1903,  p.  547. 

28.  Neuere  Forschungen  iiber  die  Befruchtung  bei  Protozoen.     Verb. 

deutsch.  Zool.  Ges.,  1905,  p.  16. 

29.  Schcel,  C.     Beitrage  zur  Fortpflanzung  der  Amoeben.     Fest.  Kupffer,  1899, 

p.  569. 

30.  Schubotz,  H.      Beitrage  zur  Kenntniss  der  Amoeba  blattae  und  Amoeba 

proteus.     Arch.  Prot.  vi.,  1905,  p.  1. 

31.  Stole,  A.     Ueber  die  Teilung  des  Protoplasmus  in  mehrkernigen  Zustande. 

Arch.  Entw.  Mech.  xix.  p.  631. 

32.  Plasmodiogonie.     Arch.  Entw.  Mech.  xxi.,  1905,  p.  111. 

33.  Vahlkampf,  E.     Beitrage  zur  Biologic  und  Entwickelungsgeschichte  von 

Amoeba  Umax.     Arch.  Prot.  v.,  1905,  p.  167. 

34.  Veley,  V.  H.     A  Further  Study  of  Pelomyxa.     J.  Linn.  Soc.  Zool.  xxix., 

1905,  p.  374. 

35.  Ziielzer,   M.      Beitrage   zur   Kenntniss   von   Difflugia   urceolata,    Carter. 

Arch.  Prot.  iv.,  1904,  p.  240. 

Some  of  the  more  important  recent  papers  on  the  parasitic  Amoebae  and 

36.  Schaudinn,  F.     (No.  27.) 

This  paper  contains  the  most  important  but  uniUustrated  account  of 
the  life-history  of  Endamocba  coli  and  Endamoeba  histolytica. 

37.  Schuberg,  A.    Die  parasitische  Amoben  des  menschlichen  Darmes.    Kritische 

Uebersicht.  Centrbl.  Bakter.  xiii.,  1893,  pp.  598,  654,  and  701. 

These  papers  contain  a  critical  account  of  the  literature  of  Amoebiasis 
up  to  the  year  1893. 

38.  Casagrandi,   Q.,  and  Barbagallo,  B.     Entamoeba  hominis  s.  Amoeba  coli, 

Lbsch.     Ann.  d' Igiene  sperimentale,  v.,  1897,  fasc.  i. 

This  paper  contains  a  full  account  of  Endamoeba  coli  and  its  occur- 

39.  Jilrgens.      Zur   Kenntniss   der   Darmamoben  und  der  Amoben -Enteritis. 

Verbff.  a.  d.  Gebiete  Militarsanitatswesens,  1902,  Heft  20,  p.  110. 
This  paper  contains  a  good  account  of  Endamoeba  histolytica. 

40.  Castellani,  A.      Protozoa  in  Human  Faeces.      Centralbl.  Bacter.  xxxviii., 

1905,  p.  66. 

41.  Craig,  C.  F.     A   New  Intestinal  Parasite   of  Man,   Paramocba  hominis. 

Amer.  J.  Med.  Sci.  cxxxii.,  1906,  p.  214. 

42.  Dopter,  C.     Sur  quelques  points  relatifs  a  Faction  pathogene  de  1'Amibe 

dysenterique.     Ann.  Inst.  Pasteur,  xix.,  1905,  p.  417. 

43.  Lesage,  A.     Culture  de  1'Amibe  de  la  dysenteric  des  pays  chauds.     Ann. 

Inst.  Pasteiir,  xix.,  1905,  p.  9. 


44.  Mugliston,  T.  C.,  and  Freer,  G.  D.     An  Undescribed  Form  of  Ulceration  of 

the  Large  Intestine,  probably  of  Amoebic  Origin.    J.  Trop.  Medicine,  viii., 
1905,  p.  113. 

45.  Afusgrave,    W.  E.,  and  Clegg,  M.   J.      Amoebas :   their  Cultivation  and 

Etiological  Significance.      J.    Inf.  Diseases,  ii.,  1905,  p.  334,  and  Publ. 
Bureau  Govt.  Lab.  Manila,  xviii.,  1905,  p.  5. 

References  to  the  general  treatises  of  Butschli,  Braun,  Calkins,  Cash,  Doflein, 
Jfartog,  and  Lang  will  be  found  on  p.  13. 

NOTE. — In  a  recent  paper  W.  Elpatiewsky  (Arch.  Prot.  x.,  1907,  p.  441)  has 
shown  that  Arcella  produces  small  amoeboid  gametes  (megamoebae  and  micra- 
moebae)  which  conjugate  and  form  a  zygote. 

THE  PEOTOZOA  (continued) 


THE  Eadiolaria  are  purely  marine  Gymnomyxa,  specialised  for 
pelagic  life.  The  body  is  usually  spherical  or  conical,  and  emits 
radiating  thread-like  pseudopodia.  The  cytoplasm  is  subdivided 
by  a  perforated  membranous  "  central  capsule  "  into  a  central  mass 
and  a  voluminous  mantle.  The  nucleus,  which  may  be  single  or 
multiple,  is  confined  to  the  intracapsular  region,  which  is  also  the 
seat  of  reproductive  changes,  the  extracapsular  mantle  being  con- 
cerned with  flotation,  feeding,  stimulation,  and  excretion.  A  siliceous 
skeleton  is  usually  present,  and  may  take  the  form  of  spicules, 
shells,  and  tubes  in  a  variety  of  delicate  and  exquisite  constructions. 
In  one  division  (Acantharia)  the  skeleton  consists,  so  far  as  is  known, 
of  strontium  sulphate.  In  most  Radiolaria  peculiar  nucleated  yellow 
corpuscles  are  found  in  abundance.  They  are  regarded  either  as 
"  symbiotic  algae  "  or  as  Peridinians.  Multiplication  by  fission  is 
known  in  a  few  cases ;  more  commonly  reproduction  by  spore- 
formation  has  been  observed. 


As  an  introduction  to  the  description  of  the  class  the  following 
account  of  Thalassicolla  has  been  drawn  up. 

Thalassicolla  is  a  spherical  gelatinous  Protozoon  from  3-5  mm. 
in  diameter.  In  the  warmer  waters  of  the  great  oceans  it  occurs  in 
vast  swarms  that  float  passively  at  the  surface  but  also  descend 
into  deeper  water  during  the  reproductive  phase.  It  ranges  for  some 
forty  degrees  of  latitude  on  either  side  of  the  equator,  diminishing 
in  numbers  towards  these  limits.  It  is  abundant  in  the  Faroe 
Channel  (Wolfenden,  Fowler),  and  a  stray  specimen  is  now  and 
then  recorded  from  our  coasts  (Delap  [40]). 

Thalassicolla  consists  of  two  parts — a  central  or  medullary  region 
and  a  thick  outer  or  cortical  layer.  The  two  are  separated  by  the 
central  capsule. 

The  intracapsular  mass  consists  of  a  large  centrally  placed 
nucleus  embedded  in  cytoplasm,  heavily  laden  with  concretions, 

1  By  F.  W.  Gamble,  D.Sc.,  F.R.S.,  Manchester  University. 



coloured  fat,  and  reserve  products.  The  extracapsular  cytoplasm 
is  composed  of — (1)  a  thin,  black,  fatty  assimilative  layer  or  matrix 
immediately  outside  the  central  capsule ;  (2)  a  frothy  mass  of 
mucilaginous  and  vacuolated  substanpes  secreted  by  interstitial 
cytoplasm  and  forming  the  so-called  "calymma"  ;  and  (3)  of  fine 
radiating  pseudopodia  which  arise  from  the  matrix  and  extend 
freely  into  the  water  beyond  the  gelatinous  bubbly  layer.  The 
wall  of  the  central  capsule  is  perforated  by  minute,  evenly  dis- 



FIG.  1. 

Thalassicolla  (Thalassophysa)  pelagica,  Haeckel.  x  25.  CK,  central  capsule  ;  EP,  extra- 
capsular protoplasm  ;  al,  alveoli,  carbonic  acid-holding  vacuoles  in  the  mucilaginous  calymma 
secreted  by  the  protoplasmic  network  ;  ps,  pseudopodia.  The  minute  unlettered  dots  are  the 
"  yellow  cells."  (After  Lankester.) 

tributed   pores,   and   through   these    the  intra-  and   extracapsular 
cytoplasm  are  continuous. 

If  the  central  capsule  is  shaken  out  of  its  calymmal  covering 
and  kept  under  suitable  conditions,  its  contents  are  capable  of 
regenerating  the  extracapsular  cytoplasm  within  a  week  (Verworn 
[14:]).  The  first  sign  of  this  process  is  the  protrusion  of  new  radial 
pseudopodia,  which  are  completed  in  twelve  hours.  The  basal 
ends  of  these  processes  form  or  secrete  a  layer — the  matrix — that 
invests  the  central  capsule,  and  their  radial  extensions  secrete  the 
calymma.  Finally,  vacuoles  make  their  appearance  in  the  jelly 
and  the  matrix  becomes  pigmented.  In  short,  the  extracapsular 


protoplasm  and  its  secretions  are  the  product  of  intracapsular 
activity.  The  extracapsular  cytoplasm,  on  the  other  hand,  has 
no  such  regenerative  power.  When  detached  from  the  capsule  it 
loses  its  form,  the  pseudopodia  contract,  the  vacuoles  burst,  and 
the  plasma  undergoes  granular  degeneration.  For  this  and  other 
reasons  we  may  speak  of  the  extracapsular  cytoplasm  as  the  ecto- 
plasm, and  the  intracapsular  plasma  as  the  endoplasm  ;  for  although 
the  pseudopodia  are  common  to  both  and  interconnect  them,  yet 
the  mass  of  the  calymma  is  a  secretion  specialised  for  contact  with 
the  outer  world,  and  performs  other  important  functions,  whilst  the 
endoplasm  is  less  directly  concerned  with  the  immediate  physiological 
needs  of  the  animal. 

Bionomics. — The  most  remarkable  physiological  characteristic 
of  Thalassicolla  is  its  paucity  of  reaction.  It  possesses  no  power 
of  active  movement,  and  responds  only  to  two  forms  of  external 
stimulus — vibration  and  heat ;  and  to  one  internal  agency,  namely, 
the  stimulus  of  reproduction.  Under  the  influence  of  wave-action 
Thalassicolla  sinks  till  a  calm  stratum  is  reached,  and  then  after  a 
time  ascends  to  the  surface.  Towards  small  variations  of  temperature 
it  remains  as  inert  as  toward  all  conditions  of  illumination  that 
have  so  far  been  tried ;  but  a  long-continued  application  of  tempera- 
tures above  30°  C.  or  below  2°  C.  induces  a  descent  from  the 
surface  of  the  sea-water,  and  this  is  followed  by  the  death  of  the 
animal.  The  onset  of  maturity  is  also  correlated  with  a  descent 
into  deep  water.  During  the  nutritive  phase  and  under  normal 
variations  of  vibration,  heat,  and  light,  the  station  of  TJialassicolla  is 
at  or  near  the  surface  of  the  sea. 

This  station  is  ensured  for  it  by  the  development  of  the  calymma. 
The  mass  of  this  veil  is  made  up  of  a  mucilaginous  secretion  containing 
fluid-vacuoles,  and  is  enclosed  in  a  delicate  cytoplasmic  investment, 
the  quantitative  proportion  of  which  is  in  minimal  relation  to  the 
bulk  of  its  secretions  and  vacuolar  fluid.  By  careful  observation, 
weighings,  and  experiment,  Brandt  (24)  has  shown  that  the  vertical 
movement  of  Thalassicolla  is  due  to  the  formation  and  expulsion 
of  vacuolar  fluid.  The  hydrostatical  requirements  of  the  case 
demand  that,  for  flotation  at  the  surface,  the  density  of  this  fluid 
should  be  that  of  water  saturated  with  carbonic  acid.  As  the 
physiological  probability  is  in  favour  of  this  conclusion,  we  may 
accept  Brandt's  view  as  in  all  likelihood  correct.  Assuming 
this,  then,  the  explanation  of  passive  descent  and  ascent  is  easy. 
In  calm  weather  and  through  a  considerable  range  of  temperature 
the  interchange  of  fluid  between  the  vacuole  and  the  sea  is  gradual, 
and  the  slight  wave-motion  reinforces  the  calymma  by  acting  as  a 
stimulant.  Thus  we  may  assume  the  balance  of  loss  and  gain,  and 
with  it  the  surface  position,  are  maintained.  But  the  movements 
of  larger  or  more  frequent  waves,  or  the  extremes  of  experimental 


temperature,  cause  contraction  of  the  calymmal  plasma.  The  pseudo- 
podia  are  withdrawn,  the  vacuoles  burst,  and  the  animal  descends 
until  the  calmer  zone  enables  it  to  reform  its  calymma  and  recharge 
its  vacuoles,  upon  which  it  ascends.  No  "  contractile  vacuoles " 
are  present,  but  their  place  is  taken  by  these  fluid-spaces  in  the 

Food. — The  food  of  Thalassicolla  consists  of  Copepods,  Diatoms, 
Infusoria,  and  probably  also  of  Peridiniae.  These  organisms  adhere 
to  the  surface  of  the  Kadiolaria  by  contact  with  its  sticky  pseudo- 
podia.  They  are  subsequently  enfolded  by  a  plasmic  web  and 
carried  into  the  deeper  part  of  the  calymma.  Here  a  digestive 
vacuole  is  formed,  and  the  ingested  organism  becomes  converted 
into  a  granular  mass,  which  is  disseminated,  by  division  of  the 
digestive  vacuole,  throughout  the  ectoplasm.  An  accumulation  of 
debris  may  sometimes  be  found  in  the  denser  layer  enveloping 
the  central  capsule,  and  there  is  little  doubt  that  the  products  of 
digestion  do  not  stop  here  but  are  carried  into  the  endoplasm,  for  it 
is  known  that  a  streaming  movement  occurs  along  the  pseudopodia 
that  connect  the  inner  and  outer  cytoplasm  through  pores  in 
the  capsular  wall.  Once  inside  the  capsule,  the  food  material  is 
probably  synthesised  into  the  fatty  or  proteid  masses  that  con- 
stitute reserves.  The  endoplasmic  globules  of  fat  are  usually 
coloured  with  a  pigment  that  varies  according  to  the  species  of 
Thalassicolla  under  consideration.  The  other  reserves  take  a  con- 
cretionary form  and  recall  starch  grains  in  their  stratified  composi- 
tion, though  not  in  their  reactions.  They  lie  in  vacuoles  filled 
with  a  proteid,  and  are  still  imperfectly  known  (Fig.  2,  A,  Cone.). 

Yellow  Cells. — The  ingestion  of  solid  food  is,  however,  not 
essential  to  the  life  of  Thalassicolla  for  at  least  several  months.  If 
kept  in  water  that  has  been  taken  from  the  open  sea  and  com- 
pletely filtered,  Thalassicolla  will  live  for  at  least  six  months  without 
showing  retrogressive  changes  beyond  a  shrinkage  of  calymmal 
volume.  Brandt,  who  has  carried  out  experimental  studies  on 
these  organisms  for  many  years,  states  (24)  that  if  comparable 
batches  are  maintained  in  such  filtered  water  in  darkness  and  in 
light,  the  illuminated  ones  alone  survive.  He  infers  that  Thalas- 
sicolla under  these  conditions  lives  upon  food  which  is  in  some  way 
elaborated  under  the  influence  of  light ;  and  in  point  of  fact  such 
a  substance — starch — does  exist  in  the  ectoplasm.  It  occurs  both 
free  in  the  capsular  layer  and  imbedded  in  the  substance  of  certain 
corpuscles  which  are  scattered  through  the  calymma  and  are 
known  as  the  "  yellow  cells."  The  significance  of  these  cells  or 
"  zooxanthellae  "  is,  in  Brandt's  view,  a  nutritive  one. 

That  these  bodies  are  independent  organisms  living  in  association 
with  Thalassicolla  and  are  not  part  of  it  was  proved  by  Cienkowski  (6). 
They  are  spherical  structures  '015  mm.  in  diameter,  and  consist  of 



a  cellulose  wall,  two  chloroplasts  marked  by  diatomin  or  an  allied 
pigment,  a  pyrenoid,  starch  of  hollow  and  solid  varieties,  and  a 
nucleus.  During  the  life  of  their  host  the  zooxanthellae  multiply 
by  transverse  fission.  After  its  death  they  pass  into  a  "palmella 
state  "  characterised  by  a  mucilaginous  jelly,  and  from  this  they 
often  escape  as  active  biflagellated  zoospores. 

Such  zooxanthellae  are  frequent  though  not  constantly  present 
in  Thalassicolla.  In  T.  nudeata  they  may  be  plentiful,  scarce,  or 
absent.  In  most  species  they  occur  unfailingly ;  sometimes  in  the 
outermost  jelly,  sometimes  in  radial  masses  throughout  the  calymma, 
or  aggregated  round  the  capsule,  but  never  within  it.  The  adapta- 
tion of  their  host  to  surface  life  meets  the  requirements  of  the 
yellow  cells  for  light,  oxygen,  and  no  doubt  other  unascertained 
demands,  with  the  result  that  the  association  has  been  regarded  as 
one  of  mutual  advantage,  as  a  case  of  symbiosis. 

The  more  recent  work  of  Famintzin  (13)  has,  however,  tended 
to  diminish  the  importance  of  the  part  which,  according  to  Brandt, 
is  played  by  the  abundant  starch  of  the  yellow  cells  in  nourishing 
their  host.  According  to  the  later  writer,  the  nutrition  of  Thalassi- 
colla is  mainly  derived  from  ingested  organisms,  and  is  only  aided 
by  the  yellow  cells  in  as  far  as  these  bodies  are  digested  by  the 
ectoplasm.  It  is  probable,  though  exact  demonstration  is  as  yet 
wanting,  that  in  some  diffusible  state  exchange  of  material  does  take 
place  from  zooxanthella  to  host  without  involving  the  death  and 
digestion  of  the  former.  Such  a  relation,  however,  does  not  explain 
the  presence  of  the  yellow  cells  in  Radiolaria.1 

Respiration. — The  researches  of  Vernon  (22)  have  shown  that 
gelatinous  or  mucilaginous  pelagic  animals  have  a  high  rate  of 
destructive  metabolism,  and  that  the  amount  of  oxygen  absorbed 
per  unit  of  dry  body -weight  is  further  increased  in  the  smaller 
animals  as  compared  with  the  larger  members  of  the  same  group, 
and  in  those  of  warmer  seas  as  against  their  cold-water  relatives. 
The  maximum  relative  absorption  of  oxygen  amongst  inverte- 
brate planktonic  animals  is  reached,  according  to  Vernon,  in  the 
Radiolaria.  Collozoum,  a  near  ally  of  Thalassicolla,  has  the  highest 
coefficient  of  all  invertebrates,  equivalent  to  forty  times  that  of 
the  frog ;  and  although  it  is  desirable  to  have  further  evidence 
before  accepting  this  startlingly  high  figure,  yet  the  evidence  of  other 
pelagic  forms  points  unmistakably  to  a  very  large  consumption  of 

The  recent  work  of  Putter  (43)  has  emphasised  the  singular 
nature  of  Protozoon  respiration.  It  has  long  been  known  that 
many  of  these  organisms  can  live  for  a  time  as  anaerobes,  and  it 
now  appears  that  intramolecular  respiration  obtains  in  a  great 
number  of  cases  and  to  an  unexpected  extent.  Fresh  energy  is  set 
1  For  a  discussion  of  the  origin  of  the  association  see  below,  p.  129. 


free  during  the  decomposition  of  reserve  materials,  and  so  long  as 
the  waste  products  evolved  in  this  process  are  removed,  respira- 
tion will  continue  in  a  medium  deprived  of  free  oxygen.  Such  a 
view  enables  us  to  consider  the  reserve  materials  of  Radiolaria 
as  of  respiratory  as  well  as  of  nutritive  significance.  It  is  not 
improbable  that  the  respiration  of  the  endoplasm  (in  which  these 
fatty  and  stratified  reserves  occur)  is  of  a  different  character  from 
the  more  violent  exchange  which  seems  to  occur  in  the  ectoplasm. 

In  connection  with  destructive  metabolism  we  may  summarise 
our  view  on  the  nature  of  excretory  processes  in  Thalassicolla.  That 
carbonic  acid  and  nitrogenous  excreta  are  formed  in  abundance 
seems  certain  from  the  rapid  destruction  and  regeneration  of  the 
calymma  and  its  vacuoles,  but  there  is  no  accumulation  of  excretory 
substances  such  as  occur  in  most  Rhizopods.  It  is  suggested,  on 
the  basis  of  experiments  with  Turbellaria  (Gamble  and  Keeble  [41]), 
that  this  absence  of  excretory  matter  is  due  to  the  activity  of  the 
yellow  cells,  which  are  attracted  to  their  host  chemotactically  and 
from  which,  by  the  uric  acid  or  urea  therein,  they  derive  their  nitrogen. 
In  the  same  way  such  a  view  affords  an  explanation  of  the  associa- 
tion of  zooxanthellae  with  Radiolaria,  and  of  the  apparently  con- 
comitant absence  of  excretory  granules.  Additional  proof  of  the 
correctness  of  this  view  lies  in  the  fact  that  such  granules  occur 
massively  and  constantly  in  one  division  of  the  Radiolaria  (the 
Phaeodaria  or  Tripylaria),  and  that  in  this  division,  and  in  this 
only,  zooxanthellae  are  as  constantly  absent. 

Reproduction. — In  addition  to  multiplication  by  simple  fission 
(25a),  Thalassicolla  has  two  true  reproductive  processes,  which,  how- 
ever, never  occur  in  the  same  individual.  These  processes  con- 
cern the  formation  of  spores,  which  are  of  two  kinds,  isospores 
And  heterospores.  A  given  Thalassicolla  is,  therefore,  isosporous  or 

When  the  reproductive  period  ensues,  the  protoplasm  and  its 
contents  undergo  a  metamorphosis,  which  results  in  the  transforma- 
tion of  the  endoplasm  into  a  mass  of  flagellated  spores,  in  the  dis- 
integration of  the  calymma,  and  the  separation  of  the  sporulating 
capsule  from  its  envelope.  The  relatively  heavy  capsule  descends 
to  a  depth  of  300-400  metres,  its  wall  bursts,  and  its  spores  are 
liberated.  In  the  case  of  isospores  these  bodies  are  of  uniform 
shape  and  size  (Fig.  2,  D) ;  in  the  case  of  heterospores  (L,  M)  two 
varieties  occur,  of  which  the  larger  are  not  only  twice  the  size  of 
the  smaller  ones,  but  possess  other  distinctive  characters  which  are 
given  below. 

The  formation  of  isospores  in  Thalassicolla  nucleata  proceeds  as 
follows  (Brandt  [26]).  The  nucleus  and  endoplasm  undergo  a 
series  of  changes.  The  chromatin,  previously  coiled  up  in  a  thick 
thread,  becomes  evenly  granular,  and  the  nucleoplasm  acquires  an 

almost  homogeneous  and  doubly  refractive  character,  and  becomes 
irregular  in  shape  as  its  membrane  disappears.  By  what  appears 
to  be  amitotic  division  the  nucleus  fragments  into  a  large  number 
of  equivalent  pieces,  each  of  which  behaves  as  an  independent 
nucleus,  and  by  further  division  these  nuclei  become  disseminated 
through  the  endoplasm.  Around  each  nucleus  the  cytoplasm  con- 
denses to  form  an  ovoid  mass,  which  is  differentiated  at  the  nuclear 
pole  into  two  cilia.  Meantime  the  reserve  materials  of  the  endo- 
plasm become  subdivided  and  apportioned,  so  that  each  isospore 
contains  a  few  granules  of  fat  and  a  crystalloid.  These  changes 
may  be  followed  on  the  accompanying  figures  (Fig.  2,  A-D). 

The  development  of  heterospores  in  Thalassicolla  proceeds  in  a 
different  manner  and  from  distinct  individuals.  The  first  step  is 
the  formation  of  a  nuclear  figure.  A  clear  achromatic  vesicle 
(centrosome,  Brandt,  1905)  arises  in  the  nucleus  and  becomes 
surrounded  by  granular  radiations,  upon  which  the  thick  bent 
chromatin  threads  arrange  themselves  as  in  Fig.  2,  E.  The  centro- 
some now  shifts  towards  the  margin  of  the  nucleus,  and  the  more 
peripheral  chromosomes  become  lumpy  and  slightly  vacuolated. 
The  nuclear  wall  softens,  and  through  it,  at  one  pole,  pass  the 
centrosome  and  a  few  apical  chromatin  granules.  Subsequently  the 
nuclear  sap  escapes  over  the  entire  periphery  of  the  nucleus, 
together  with  much  of  the  granular  nuclear  matrix,  into  the  sur- 
rounding endoplasm.  The  chromatin  threads  fragment  and  the 
fragments  become  associated  with  segregated  masses  of  fine  nuclear 
granules  to  form  organised  nuclei,  Avhich  divide  mitotically.  During 
this  process  the  nuclei  are  carried  outwards  in  increasing  numbers 
towards  the  wall  of  the  central  capsule,  where  they  become 
arranged  in  columns,  until  almost  the  whole  of  the  original  nucleo- 
plasm  is  used  up.  The  most  remarkable  features  of  this  organising 
process  is  that  the  developing  nuclei  are  of  two  sizes,  which  are 
severally  aggregated  in  the  peripheral  columns.  Meantime  the 
endoplasm  and  its  reserves  have  been  mobilised.  The  former  is 
converted  into  cylinders  around  the  mega-  or  micro-nuclei,  and 
within  these  cylinders  the  fat  and  crystalloids  become  fragmented 
and  distributed.  Finally,  by  subdivision  of  these  nucleated  masses 
colonies  of  mega-  and  micro-spores  arise.  Both  are  biciliate,  and  in 
comparison  with  isospores  minute,  and  divided  by  a  groove  into  a 
reniform  shape.  The  microspores  are  from  O'OOS  to  O'Ol  mm.  in 
length,  the  megaspores  O'Ol 6  to  O'Ol 7.  The  microspores  have  a 
deeply  staining  granular  nucleus  and  a  cytoplasm  free  from  inclu- 
sions except  for  one  or  two  minute  crystalloids.  The  megaspores, 
on  the  other  hand,  possess  a  nucleus  poor  in  chromatin,  and  their 
cytoplasm  is  crowded  with  refringent  corpuscles.  Both  forms  of 
heterospore  have  the  same  ciliary  mechanism  (Fig.  2,  L).  From 
one  point  in  the  groove  two  long  cilia  arise,  one  of  which  works 


FIG.  2. 

The  development  of  isopores  and  heterospores  in  Thalassicolla  nudeata.  (After  Brandt,  1905.) 
A-C,  isospore-fonnation,  xlOO.  The  large  nucleus  (N)  breaking  up  into  spore  nuclei  (N.  Isp). 
1),  an  isospore  (x  2000);  Cone,  stratified  concretions  lying  in  proteid  vacuoles.  E-K,  hetero- 
spore  -  formation,  x  100.  E,  nuclear  membrane  collapsing.  Nuclear  figure  and  one  intra- 
nuclear centrosome.  F,  diffusion  of  nucleoplasm  (A'w)  outwards.  G,  organisation  of  second- 
ary nuclei  (Ao).  H  and  K,  segregation  of  these  nuclei  to  form  heterospore  nuclei.  L,  mega- 
spores.  This  figure  shows  the  two  flagella  arranged  like  those  of  a  Dinoflagellate.  M,  micro- 
spores.  L,  M,  x  1000. 



horizontally  and  is  coiled  round  the  body  of  the  spore,  the  other 
projects  freely  outwards  and  backwards.  Consequently,  as  these 
minute  structures  dart  or  vibrate,  they  rotate  unceasingly  about 
their  long  axis,  the  whole  mechanism  and  display  recalling  those 
of  certain  Peridiniae. 

The  further  history  of  the  iso-  and  heterospores  is  unknown. 
Brandt's  recent  attempts  (26)  to  obtain  conjugation  between  spores 
of  the  same  and  of  different  individuals  have  been  as  futile  as  those 
of  earlier  observers.  If,  however,  we  may  judge  by  the  analogy  of 
other  Protozoa,  and  in  particular  by  the  life -history  of  Tricho- 
sphaerium  (Schaudinn  [42]),  we  may  presume  that  the  heterospores 
are  male  and  female  gametes,  and  that  the  isospores  are  asexual  indi- 
viduals. But  on  this  question,  as  on  the  further  one  of  a  suggested 
alternation  between  isosporous  and  heterosporous  generations  of 
Thalassicolla,  we  still  lack  information. 

1,  central  capsule  of  Thalassicolla  nucleata,  Huxley,  in  radial  section,  x  100 ;  a,  the 
large  nucleus  (Binnenblaschen) ;  6,  proteid  vacuoles  of  the  intracapsular  protoplasm  con- 
taining concretions ;  c,  wall  of  the  capsule  (membranous  shell),  showing  the  fine  radial  pore- 
canals  ;  d,  chromatin  substance  of  the  nucleus.  2,  3,  Collozoum  inerme,  J.  Miiller,  two  different 
forms  of  colonies,  of  the  natural  size.  4,  central  capsule  from  a  colony  of  Collozoum  inerme, 
showing  the  intracapsular  protoplasm  and  nuclei,  broken  up  into  a  number  of  isospores,  each 
of  which  encloses  a  crystal  of  strontium  sulphate ;  c,  yellow  cells  lying  in  the  extracap.sular 
protoplasm.  5,  a  small  colony  of  Collozoum  inerme,  magnified  25  diameters ;  a,  alveoli 
(vacuoles)  of  the  extracapsular  protoplasm  ;  b,  central  capsules,  each  containing  besides  proto- 
plasm a  large  oil-globule.  6-13,  yellow  cells  of  various  Radiolaria.  6,  normal  yellow  cell ; 
7,  8,  division  with  formation  of  transverse  septum  ;  9,  a  modified  condition  according  to 
Brandt;  10,  division  of  a  yellow  cell  into  four;  11,  amoeboid  condition  of  a  yellow  cell  from 
the  body  of  a  dead 'Sphaerozoon  ;  12,  a  similar  cell  in  process  of  division  ;  13,  a  yellow  cell  the 
protoplasm  of  which  is  creeping  out  of  its  cellulose  envelope.  14,  Heliosphaera  inermis,  Haeck., 
living  example,  X400;  a,  nucleus;  6,  central  capsule;  c,  siliceous  basket-work  skeleton. 
15,  two  isospores  of  Collozoum  inerme,  set  free  from  such  a  central  capsule  as  that  drawn  in  4; 
each  contains  a  crystal  6  and  a  nucleus  a.  16,  two  heterospores  of  Collozoum  inerme,  of  the 
second  kind,  viz.  devoid  of  crystals ;  and  of  two  sizes,  a  megaspore  and  a  microspore.  They 
have  been  set  free  from  central  capsules  with  contents  of  a  different  appearance  from  that 
drawn  in  4.  o,  nucleus.  17,  Actinomma  asteracanthion,  Haeck.,  x260  ;  one  of  the  Peripylaria. 
Entire  animal  in  optical  section,  o,  nucleus  ;  b,  wall  of  the  central  capsule  ;  innermost  siliceous 
shell  enclosed  in  the  nucleus  ;  c1,  middle  shell  lying  within  the  central  capsule  ;  c2,  outer  shell 
lying  in  the  extracapsular  protoplasm.  Four  radial  siliceous  spines,  holding  the  three  spherical 
shells  together,  are  seen.  The  radial  fibrillation  of  the  protoplasm  and  the  fine  extracapsular 
pseudoppdia  are  to  be  noted.  IS,  Amphilonche  messanensis,  Haeck.,  x  200;  one  of  the  Acan- 
thometrida.  Entire  animal  as  seen  living.  (After  Lankester.) 


The  Radiolaria  may  be  derived  from  such  an  organism  as 
Thalassicolla  by — (1)  fission  and  the  formation  of  a  colony  of  similar 
or  dimorphic  individuals  imbedded  in  a  voluminous  communal  jelly 
(Sphaerozoa  or  polyzoic  Radiolaria) ;  (2)  by  differentiation  of  the 
openings  of  the  central  capsule  from  its  evenly  porose  condition 
(Peripylaria)  to  a  radially  segregated  oligo-porose  type  (Acantharia), 
to  a  single  pore-plate  at  one  pole  of  the  now  asymmetrical  capsule 
(Monopylaria),  or  to  a  single  main  aperture  and  two  lateral  ones 
(Tripylaria) ;  (3)  by  differentiation  in  the  ectoplasm  of  skeletal 
spicules  and  shells  of  the  most  diverse  forms,  which  only  in  the 
Acantharia  invade  the  endoplasm. 


Amongst  the  most  primitive  Radiolaria  are  the  Physematiidae 
and  the  allied  families  Thalassicollidae,  Thalassophysidae,  etc.  In 
all  these  forms  the  hydrostatic  jelly  is  so  well  developed  as  to  give 
the  term  Collodaria  to  the  order  formed  by  them.  In  the  first 
family,  however,  the  vacuoles  elsewhere  found  in  the  ectoplasm  are 
endoplastic  products,  no  stratified  nutritive  concretions  are  found, 
and  yellow  cells  are  absent.  The  skeleton,  if  present,  consists 
merely  of  scattered  spicules.  These  organisms  belong  to  the 
surface  strata  of  the  ocean  and  are  phosphorescent.  Their  life- 
history  falls  into  well-marked  nutritive  and  reproductive  phases. 
The  early  nutritive  stage  was  erected  by  Haeckel  into  a  special 
genus  Actissa,  which  Brandt  has  shown  to  be  a  phase  of  growth 
that  occurs  in  at  least  two  of  the  five  families.  The  later  nutritive 
stage  differs  in  few  characters  from  that  of  Thalassicolla.  The  Phy- 
sematiidae afterwards  pass  into  an  isosporous  reproductive  phase ; 

FIG.  4. 

1,  Lithocircus  annularis,  Hertwig ;  one  of  the  Monopylaria.  Whole  animal  in  the  living 
state  (optical  section),  a,  nucleus ;  6,  wall  of  the  central  capsule ;  c,  yellow  cells ;  d,  per- 
forated area  of  the  central  capsule  (Monopylaria).  2,  Cistidium  ine.rme,  Hertwig ;  one  of 
the  Monopylaria.  Living  animal.  An  example  of  a  Monopylarion  destitute  of  skeleton,  a, 
nucleus  ;  b,  capsule  wall ;  c,  yellow  cells  in  the  extracapsular  protoplasm.  3,  Carpocanium 
diadema,  Haeck.  ;  optical  section  of  the  beehive-shaped  shell  to  show  the  form  and  position  of 
the  protoplasmic  body,  a,  the  tri-lobed  nucleus  ;  b,  the  siliceous  shell ;  c,  oil-globules  ;  d,  the 
perforate  area  (pore-plate)  of  the  central  capsule.  4,  Coelodendron  gracillimum,  Haeck.  ;  living 
animal,  complete  ;  one  of  the  Tripylaria.  a,  the  characteristic  dark  pigment  (phaeodium) 
surrounding  the  central  capsule  b.  The  peculiar  branched  siliceous  skeleton,  consisting  of 
hollow  fibres,  and  the  expanded  pseudopodia  are  seen.  5,  central  capsule  of  one  of  the 
Tripylaria,  isolated,  showing  a,  the  nucleus ;  6,  c,  the  inner  and  the  outer  laminae  of  the 
capsule  wall ;  d,  the  chief  or  polar  aperture ;  e,  e,  the  two  secondary  apertures.  6,  7,  Acan- 
thometron  Claparedei,  Haeck.  7  shows  the  animal  in  optical  section,  so  as  to  exhibit  the 
characteristic  meeting  of  the  spines  at  the  central  point  as  in  all  Acanthometrida ;  a,  small 
nuclei ;  b,  a  parasite  (Amoebophrya)  ;  c,  wall  of  the  central  capsule  ;  d,  extracapsular  jelly  ; 
e,  peculiar  intracapsular  yellow  cells.  8,  Spongosplinera  streptacantha,  Haeck.  ;  one  of  the 
Peripylaria.  Siliceous  skeleton  not  quite  completely  drawn  on  the  right  side,  a,  the  spherical 
extracapsular  shell  (compare  Fig.  3  (17)),  supporting  very  large  radial  spines  which  are  con- 
nected by  a  spongy  network  of  siliceous  fibres.  9.  Aulosplutera  degantissima,  Haeck. ;  one 
of  the  Phaeodaria.  Half  of  the  spherical  siliceous  skeleton.  (After  Lankester.) 

the  Thalassicollidae  into  either  isosporous  or  heterosporous  modes 
of  reproduction ;  and  the  Thalassophysidae  fragment  suddenly  into 
hundreds  of  minute  pieces  (see  pp.  137-8),  without  passing,  so  far  as 
is  known,  into  a  sporulating  phase. 

In  the  next  division  (Sphaerozoa)  the  polyzoic  condition  is 
characteristic  of  the  nutritive  phase.  The  colony  or  coenobium  is 
spherical,  elongate,  or  moniliform,  though  the  individuals  may 
retain  the  primitive  homaxonic  symmetry  (Collosphaeridae)  or 
become  flattened  (Sphaerozoidae).  The  skeleton  may  be  absent, 
spicular,  or  spheroidal,  and  the  scattered  "  nuclei "  are  homogeneous 
lumps  of  chromatin. 

The  life-history  of  the  Sphaerozoa  is  still  incompletely  known, 
though  much  has  been  done  by  Brandt  (1885)  to  follow  it.  Accord- 
ing to  this  writer  three  kinds  of  sexual  individuals  or  colonies 
occur  : — isosporous  forms,  heterosporous  forms  produced  directly, 
and  heterosporous  forms  produced  after  gemmation.  In  the  Sphaero- 


zoidae  both  megaspores  and  microspores  arise  in  the  same  individual  j 
isospores  in  different  individuals.  Moreover,  the  asexual  individuals 
are  not  all  alike,  but  in  certain  genera  at  least  some  produce  extra- 
capsular  bodies  (pp.  138-9),  and  those  individuals  which  bud  off  these 
structures  are,  according  to  Brandt,  young  forms.  These  fertile 
young  forms  become  in  many  cases  heterosporous  —  the  extra- 
capsular  body  forming  the  megaspores,  the  intracapsulum  giving 
rise  to  the  microspores — but  in  other  cases  the  extracapsiilar  bud 
develops  into  a  new  central  capsule.  Consequently  we  have  two 
forms  of  heterosporous  individuals  and  one  isosporous  form,  and 
Brandt  suggests  that  there  is  an  alternation  between  the  hetero- 
sporous and  homosporous  individuals.  Famintzin,  however,  has 
reinvestigated  the  matter,  and  finds,  in  the  vast  numbers  of  full- 
grown  colonies  that  occur  in  autumn  at  Naples,  some  are  converted 
into  isospores,  some  into  heterospores,  and  many  have  extracapsular 
bodies.  These  last  colonies  divide  into  small  winter  ones,  the 
majority  of  which  possess  extracapsular  buds  and  develop  into 
heterosporous  forms.  According  to  Famintzin  there  is  no  alter- 
nation of  generations  (13). 

Whilst  the  Sphaerozoidae  thus  either  become  heterosporous 
directly,  or  indirectly  after  division  and  the  development  of  extra- 
capsular bodies,  the  Collosphaeridae  have  no  extracapsular  buds, 
and  their  mega-  and  microspores  develop  in  separate  individuals. 
The  skeleton  when  present  takes  the  form  of  a  perforated  shell, 
but  notwithstanding  these  differences  they  are  held  to  be  rightly 
separated  from  the  Sphaerellaria,  with  which  Haeckel  formerly 
united  them. 

The  Sphaerellaria  include  an  immense  number  of  solitary 
chambered  forms,  the  majority  of  which  are  spherical,  the  remainder 
being  elliptical  or  flattened.  Eadial  bars  unite  the  chambers,  but 
these  bars  are  wholly  ectoplasmic,  and  are  never  joined  at  the  centre 
of  the  endoplasm  as  in  certain  Acantharia.  The  nucleus  remains- 
single,  but  grows  with  the  growth  of  the  individual. 

The  Acantharia  form  a  primitive  group  of  Eadiolaria  with  many 
interesting  distinctive  features.  They  retain  homaxonic  symmetry, 
but  the  pores  of  the  central  capsule  are  less  closely  set  than  in  the 
Spumellaria.  Through  these  pores  there  pass  not  only  the  cyto- 
plasmic  bridges  between  ectoplasm  and  endoplasm,  but  also  two- 
other  radiating  structures,  namely,  stiff  pseudopodia  (axopodia)  and 
spicules.  The  latter  meet  in  the  centre  of  the  capsule  (Fig.  4  (7)), 
the  former  surround  the  centre  and  alternate  with  the  spicules 
(Fig.  18),  which  pass  outwards  generally  in  five  whorls.  These 
emerge  from  the  ectoplasmic  surface  at  points  through  which  five 
circles  could  be  inscribed  corresponding  to  the  two  tropical,  two 
polar,  and  equatorial  lines  of  the  globe. 

The  whole   disposition    strongly   suggests    that   the   radiating 



spicules  have  developed  by  a  hardening  of  the  stiff  fibre  of  certain 
alternate  axopodia  which  formerly  met  at  the  centre  of  the  endo- 
plasm  as  in  Heliozoa,  to  which  group  this  order  suggests  other 
points  of  affinity.  The  peculiar  nature  of  these  spicules  is  the 
distinguishing  feature  of  the  order.  They  are  composed,  in  the 
best  investigated  cases,  of  strontium  sulphate  (Biitschli,  1906),  and 
not  of  a  chitinoid  organic  acanthin-substance,  as  Haeckel  supposed. 

Fio.  5. 

To  illustrate  the  structure  of  the 
Nassellarian  sub-family.  A,  Plagonis- 
cu,s  tripodiscus,  II.,  showing  the  central 
capsule  (c.c)  supported  by  the  skeletal 
tripod.  B,  Cortina  typus,  H.,  showing 
the  tripod  and  sagittal  ring  (5)  enclos- 
ing the  central  capsule,  within  which 
are  seen  the  podocone  (p),  the  nucleus 
above,  and  three  oil -globules.  C,  Tre- 
pospyris  cortiniscvs,  H.,  to  show  the 
formation  of  the  helmet-like  type  of 
skeleton  from  the  tripod  and  sagittal 
ring.  (After  Haeckel. ) 

The  nucleus  is  a  multiple  structure,  and  the  large  body  frequently 
mistaken  for  a  nucleus  (Fig.  4  (6,  &))  is  a  Suctorian  parasite.  The 
Acantharia  frequent  the  upper  layers  of  the  ocean  (chiefly  from 
the  surface  down  to  300  metres),  and  are  abundant  in  Arctic  and 
Antarctic  seas  as  well  as  in  the  intermediate  zones.  The  yellow 
cells  that  in  other  Radiolaria  are  confined  to  the  extracapsulum, 
occur  almost  exclusively  within  the  central  capsule  in  the 

The  Monopylaria  or  Nassellaria  include  an  immense  range  of 
forms.  In  the  simplest  the  central  capsule  is  supported  by  a 
siliceous  tripod  or  tetrad  spicule,  often  accompanied  by  a  sagittal  ring. 



It  contains  a  peculiar  cone  of  doubtful  significance  (Fig.  5,  B,  p). 
The  ectoplasm  streams  out  from  the  capsular  pore-plate  and  forms  a 
dense  bubbly  mass  around  this  opening.  From  this  point  it  passes 
as  a  thin  layer  around  the  capsule,  so  that  the  cytoplasm  is  asym- 
metrically distributed.  These  Radiolaria  are,  in  fact,  bilaterally 
symmetrical.  Lateral  outgrowths  from  the  spicule  or  sagittal  ring 
give  rise  to  a  helmet-like  shell  or  "cephalis,"  in  the  upper  part 

Eucyrtidium  cranioides,  Haeck.,  x  150;  one  of  the  Monopylaria.  Entire  animal  a.s  seen  in 
the  living  condition.  The  central  capsule  is  hidden  by  the  beehive-shaped  siliceous  shell 
withinlwhich  it  is  lodged. 

of  which  the  central  capsule  is  lodged.  The  cephalis  becomes 
voluminous  and  often  constricted,  producing  a  vast  array  of  specific, 
skeletal  variety,  the  whole  of  which  is  produced  by  modification  of 
a  single  spicule.  The  nucleus,  though  often  lobed,  remains  single. 
Spore-formation  is  known  to  occur,  but  no  form  of  reproduction  has 
been  adequately  investigated.  The  bionomics  of  the  group  are 
quite  unknown. 

The  Tripylaria  or  Phaeodaria  form  another  large  group,  most 



easily  characterised  by  the  brown,  greenish-brown,  or  black  accumu- 
lation of  food  material,  debris,  and  resistant  "  phaeodellae  "  that  lie 
in  the  oral  half  of  its  ectoplasm ;  and  they  are  also  signalised  by 
the  mode  of  distribution  of  the  capsular  pores.  In  the  majority  of 
genera  the  endoplasm  communicates  with  the  ectoplasm  only  by 
a  teat-like  operculum  and  a  pair  of  small  lateral  conical  pores 
(the  so-called  astropyle  and  parapyles).  In  a  few  cases  two 
astropyles  occur,  and  in  at  least  one  genus  (Atlanticella)  only  a 
single  pore-plate  is  present.  The  skeleton  varies  greatly  in  structure 


S^ Pfi 

Fio.  7. 

Aulactiniuin  actinastrum,  H. ;  a  member  of  the  Phapodaria.  (After  Haeckel,  slightly 
modified.)  A,  astropyle ;  C,  calymma ;  AT,  double  nucleus  lying  in  the  endoplasm  ;  P, 
parapyle ;  PJi,  phaeodium. 

and  configuration.  It  is  usually  of  a  tubular  nature,  and  the  hollow 
cylinders  are  often  subdivided  by  septa.  The  basis  of  these 
tubes,  however,  is  formed  by  minute  aciculate  spicules  which  are 
surrounded  by  a  gelatinous  sheath,  and  between  this  sheath  and 
the  surrounding  ectoplasmic  matrix  is  a  thin  membrane,  which  first 
becomes  silicified.  This  is  followed  by  deposition  of  silica  in  the 
gelatinous  sheath,  and  in  this  way  complex  spicules,  often  with 
candelabra-like  appendages,  are  developed.  A  single  or  double  per- 
forated shell  may  be  present,  the  surface  of  which  has  a  peculiar 
porcellanous  appearance  and  "  diatomaceous  "  structure.  In  the 


most  complex  Phaeodaria  this  shell  acquires  a  bivalvular  form  and 
carries  many  peculiar  processes  (Fig.  32). 

The  nucleus  is  a  large,  usually  single  structure,  and  undergoes 
a  peculiar  kind  of  mitosis  accompanied  by  the  formation  of  a  great 
number  of  chromosomes.  The  development  and  nature  of  the 
spores  is  incompletely  known.  A  characteristic  feature  of  this 
order  is  the  absence  of  the  yellow  cells  that  occur  almost  constantly 
in  the  other  orders.  This  negative  feature  appears  to  be  correlated 
with  the  presence  of  that  remarkable  and  still  imperfectly  analysed 
complex,  the  phaeodium.  The  researches  of  Borgert  (18)  give 
some  ground  for  thinking  that  the  phaeodellae  (see  p.  119)  are 
excreta,  and  if  so,  the  retention  of  these  substances  in  Radiolaria 
devoid  of  "  yellow  cells  "  lends  support  to  the  view,  derived  from 
a  study  of  the  Turbellaria  (Keeble  and  Gamble  [41]),  that  these 
symbiotic  algae  exert  a  depuratory  function. 

Variation:  Dimorphism. — The  Radiolaria  present  three  kinds 
of  structural  modification.  There  is  the  divergent  variation  about 
one  or  more  centres  that  constitutes  a  "  species."  There  is  racial 
somatic  dimorphism  in  relation  to  pelagic  or  abyssal  life.  And 
there  is  gametic  dimorphism  both  in  early  and  adult  stages  of  life 
in  relation  to  reproduction. 

The  conception  of  "  species "  in  Radiolaria  is  only  gradually 
assuming  a  form  similar  to  that  held  in  the  case  of  other  Protozoa. 
Hitherto  skeletal  characters  have  been  mainly  and  rigidly  employed 
for  the  erection  of  a  vast  number  of  specific  forms.  The  larger 
collections  made  by  Plankton  expeditions  of  recent  years  have 
shown  that  many  of  these  earlier  species,  and  even  genera,  are 
either  growth  stages  of  one  and  the  same  form,  fission  products 
common  to  several  species,  or  divergent  variations  referable  to  a 
central  "  type."  The  first  kind  of  variation  probably  occurs  in 
every  Radiolarian  and  has  been  recently  worked  out  for  several 
Tripylaria  (Immermann).  In  Aulokleptes  flosculus,  for  example, 
spicules  of  three  kinds  can  be  met  with,  each  one  of  which  was  the 
basis  of  a  separate  species  in  Haeckel's  classification.  It  has  been 
shown,  however,  by  Immermann  that  the  spicules  pass  through  two 
or  more  forms  before  arriving  at  their  definitive  stage,  and  may  be 
arrested  at  an  intermediate  stage.  Further  knowledge  of  the 
development  of  the  skeleton  will  undoubtedly  tend  to  diminish  the 
profusion  of  species  that  Haeckel  has  proposed.  But  it  is  not 
skeletal  characters  only  that  are  subject  to  change  during  growth. 
Among  the  Collodaria,  in  which  the  spicules  are  a  subordinate  feature 
and  in  some  families  entirely  absent,  the  early  stages  of  growth 
differ  so  greatly  from  the  later  ones  as  to  render  their  identification 
a  difficult  matter  and  one  particularly  liable  to  misinterpretation. 
Thus  the  genus  Adissa,  which  Haeckel  brought  forward  as  the 
most  primitive  of  all  Radiolaria,  has  been  shown  by  Brandt  (25)  to 



be  an  early  stage  in  species  of  the  two  families  Thalassophysidae 
and  Physematiidae.  Even  the  presence  of  developmental  stages  is  not 
decisive  proof  that  the  fertile  protoplast  or  coenobium  in  question 
is  a  final  stage  in  the  life-history,  since  in  certain  forms  1  an  early 
and  variable  reproductive  stage  is  intercalated  between  the  earliest 
phase  and  that  of  full  growth.  Fission  introduces  further  com- 
plexities. The  Acantharian  genus  Litholoplms  was  founded  on 
stages  of  growth  or  fission  products  belonging  to  other  genera ;  and 
the  division  of  the  Collozoidae  by  fission  leads  to  minute  forms 
that  might  easily  be  mistaken  for  young  stages,  although  they  are 
reproductive  individuals.  We  are  thus  led  to  the  conclusion  that 

Fio.  8. 

Racial  dimorphism  in  Aulacantha  scolymantha,  x  26.  (After  Hacker.)  A,  deep-sea  form  ;  B, 
pelagic  form  from  Naples,  100  fathoms.  C.c,  central  capsule  ;  Exo,  ectoplasm  ;  Ph,  phaeodium  ; 
R,  radial  spicules  ;  Tf,  tangential  .spicules. 

a  knowledge  of  the  life-history  is  essential  to  the  construction  of  a 
permanent  classification,  and  that  when  this  is  obtained  the  species 
will  be  groups  segregated  about  their  several  types. 

The  dimorphism  of  Radiolaria  is  of  two  kinds  :  somatic  and 
gametic.  Somatic  dimorphism  is  at  present  known  only  in  few 
instances.  It  consists  in  the  development  of  a  small  race  of  a 
widely  ranging  species  in  warmer  surface  water,  and  of  a  large  race 
(usually  three  times  the  size  of  the  former)  in  cold  and  deep  water. 
Associated  with  these  differences  of  size  there  is  structural  diversity. 
The  spicules  of  the  small  race  are  fewer  and  simpler,  the  ectoplasm 
they  support  is  delicate  and  limp,  often  sagging  between  the 

1  E.g.  Collosphaera  (Fig.  15,  A). 



FIG.  9. 

Radial  spicules  of  A,  abyssal  form  of  Auloscena 
vertitillatus ;  B,  pelagic  form.    (After  Hacker.) 

siliceous  appendages.  The  skeleton  of  the  large  race  ends  in  more 
elaborate  constructions,  and  stretches  more  tightly  the  tougher, 
thicker  ectoplasm  that  covers  the  animal.  Such  racial  dimorphism 

is  known  in  Aulacantha  scoly- 
mantha  (Fig.  8),  Circoporus  sex- 
fuscinus,  in  Auloscena  verticilla- 
tus,  and  probably  will  be  found 
more  commonly  when  looked 
for.  Both  races  are  capable 
of  reproduction,  and  it  is  im- 
probable that  they  merge  into 
one  another,  but  it  is  not 
known  whether  the  mode  of 
reproduction  is  the  same  in 

Gametic  dimorphism  is 
more  general  and  perhaps  uni- 
versal, but  is  unaccompanied 
by  any  known  diversity  of 
somatic  structure.  It  is  there- 
fore comparable  with  the  di- 
morphism of  such  Foraminifera 
as  Discorbina  and  Truncatulina, 
and  is  signalised  by  the  formation  of  isospores  and  of  heterospores 
in  distinct  and  differently  constituted  individuals.  These  processes 
involve  the  contents  of  the  central  capsule  and  are  followed  by  the 
death  of  the  ectoplasm.  An  individual  Radiolarian  is  therefore  only 
a  phase  in  the  life-cycle  of  its  race,  but  the  changes  which  lead  up  to 
the  formation  of  isospores  are  so  distinct  from  those  that  precede  the 
development  of  heterospores,  and  involve  such  deep-seated  nuclear 
transformations,  that  it  is  difficult  to  believe  that  similar  individuals 
of  any  one  generation  can  give  rise  to  both  forms  of  spore.  On 
this  ground  Brandt  has  been  led  to  formulate  the  view  that 
isosporous  and  heterosporous  individuals  of  any  one  species  belong 
to  alternate  generations.  Direct  evidence  of  this  alternation  has  not 
been  obtained,  and  therefore  the  case  of  the  Radiolaria  is  on  a  very 
different  footing  from  the  observed  alternation  in  Foraminifera. 

Distribution :  A,  Vertical. — The  recently  published  reports  of  the 
German  Plankton  expeditions,  though  not  yet  complete,  enable  us 
to  picture  the  vertical  distribution  of  the  Radiolaria  more  accur- 
ately than  was  formerly  possible.  The  older  records  were  derived 
from  surface  townettings  and  from  Ehrenberg's  researches  on 
Radiolarian  deposits  at  varying  depths.  They  represented  the 
group  as  occurring  at  all  depths,  even  on  the  sea-bottom,  and  as 
increasing  in  variety  with  depth.  The  more  recent  exploring  ex- 
peditions give  a  very  different  result.  From  them  it  appears  that 


in  Atlantic  and  Antarctic  waters — (1)  the  majority  of  Radiolaria 
occur  not  deeper  than  400  metres ;  that  the  Collodaria  are  em- 
phatically surface  forms  characteristic  of  the  top  stratum  (0-50  m.) ; 
(2)  that  in  the  next  stratum  below  this  (50-400)  the  great  develop- 
ment of  Radiolarian,  as  also  of  diatomaceous,  life  occurs.  Here  the 
majority  of  Acantharia,  many  Spumellaria,  and  many  Phaeodaria, 
e.g.  Challengeridae,  occur;  (3)  that  in  the  still  deeper  water,  400- 
1000  metres,  a  still  richer  Phaeodarian  fauna  and  a  few  Acantharia 
are  met  with,  and  that  beyond  this  a  few  remarkable  forms  range 
down  to  5000  metres.  The  vertical  distribution  of  the  Nassellaria 
is  not  yet  adequately  known,  but  it  probably  follows  much  the 
same  lines  as  that  of  the  Phaeodaria. 

B,  Horizontal. — The  distribution  of  the  class  is  extremely  wide, 
as  is  readily  understood  from  their  dispersal  by  the  great  oceanic 
currents.  Some  forms  are  panplanktonic,  e.g.  Aulacantha ;  some 
are  bipolar:  many  are  emphatically  warm -water  forms;  others  as 
characteristically  follow  cold  currents.  Such  considerations  enable 
us  to  understand  the  varying  depths  at  which  the  same  form  may 
occur  as  its  chosen  current  occupies  now  a  deeper,  now  a  more 
superficial  position  in  the  ocean.  The  greatest  variety  of  species 
is  met  with  in  equatorial  waters,  and  this  fulness  extends  in 
diminishing  variety  north  and  south  for  some  forty  degrees.  Then 
there  follows,  at  least  in  the  northerly  direction,  as  in  the  case  of 
many  other  pelagic  orders,  a  barren  zone,  and  finally  Arctic  waters 
show  a  Radiolarian  fauna  that  is  rich  in  individuals  though  poor  in 
variety,  and  is  apparently  greatly  inferior  to  that  of  Antarctic 
(Hacker).  This  mode  of  distribution  explains  the  comparative 
poverty  of  the  British  Radiolarian  fauna.  Though  the  lack  of 
research  makes  reserve  necessary,  it  seems  certain  that  these  waters 
of  the  west  and  north-east  coasts  of  Britain  contain  only  a  casual 
Thalassicolla  and  a  few  Acanthometrida,  Sphaerellaria,  and  Phaeo- 
daria, outliers  and  stragglers  of  the  rich  Gulf  Stream  fauna. 
The  great  northern  host  passes  by  the  Faroes  and  off  the  Hebrides, 
as  the  lists,  pp.  144-151,  show,  and  in  those  waters  the  researches 
of  Murray,  Fowler,  and  Wolfenden  have  revealed  a  number  of 
interesting  forms. 

The  deposits  formed  by  the  accumulation  of  Radiolarian 
skeletons  constitute  a  well-known  element  in  the  composition  of 
littoral  and  deep-sea  Globigerina  ooze  and  of  red  clay.  They  make 
up  certain  of  the  clays,  marls,  and  pumices  found  in  the  Miocene 
deposits  of  Barbadoes,  the  Nicobar  Islands,  and  on  both  sides  of  the 
Mediterranean,  as  at  Oran  and  Tripoli.  Siliceous  organic  rocks 
of  Palaeozoic  and  of  Mesozoic  age  have  been  recently  discovered  in 
many  parts  of  the  world ;  and  microscopical  investigations  of  these 
rocks  have  revealed  an  unsuspected  wealth  of  Radiolaria  in  them. 
From  the  Cambrian  age  onwards,  however,  the  families  and  even 


genera  appear  identical  with  those  now  living.  Pre- Cambrian 
Kadiolaria  are  still  doubtful  (Hinde  [44]).  The  Sphaerellaria  (Poly- 
cystina)  and  Nassellaria  are  the  chief  contributors,  since  the 
strontium  skeletons  of  the  Acantharia  are  readily  soluble,  and 
therefore  are  unknown  in  recent  deposits  or  in  a  fossil  state,  and 
the  hollow  siliceous  spicules  of  the  Phaeodaria  also  appear  in- 
capable of  resisting  decomposition.  Many  skeletons  formerly  identi- 
fied as  Radiolarian  (such  as  Dictyota  and  Mesoscena)  are  now  referred 
to  the  Flagellata  or  to  other  orders,  but  the  Nassellaria  Cyrtoidea 
form  the  majority,  the  Sphaerellaria,  Discoidea,  and  Sphaeroidea 
the  minority,  of  Jurassic  Radiolaria  in  quartzites  and  coprolites. 
In  later  deposits  of  Miocene  ages  this  predominance  is  maintained, 
but  the  species  found  are  identical  with  or  closely  akin  to  living 

Central  Capsule. — The  cytoplasm  of  Radiolaria  is  distinguished 
from  that  of  other  Protozoa  by  the  great  development,  specialisa- 
tion, and  delimitation  of  its  ectoplasm.  The  boundary  between 
this  peripheral  layer  and  the  central  nucleated  plasma  is  almost 
always  a  distinct  one ;  and  the  few  cases  amongst  the  Acantharia 
and  Sphaerozoa  in  which  no  limiting  membrane  can  be  traced, 
serve  to  show  that  this  separation  is  the  outcome  of  more  primitive, 
undifferentiated  conditions,  which  the  Radiolaria  display  in  early 
life,  to  which  they  revert  during  fission,  and  occasionally  retain 
throughout  life. 

The  central  capsule  is  the  sign  of  this  plasmic  differentiation, 
and  the  mark  of  a  Radiolarian.  It  consists  of  a  single,  or  in 
Phaeodaria  of  a  double,  porous  membrane  of  either  chitinoid  or 
mucinoid  nature.  Usually  the  capsule  is  of  such  tenuity  as  to  be 
visible  only  after  the  use  of  reagents,  or,  as  in  Thalassicolla,  it  may 
be  comparatively  thick  and  areolated  by  the  growth  of  ridges  on 
its  inner  surface  (Hertwig). 

The  shape  of  the  capsule  is  in  general  correlated  with  that  of 
the  configuration  of  the  animal.  In  homaxonic  Spumellaria  and 
Acantharia  it  is  spherical ;  in  lenticular  and  discoid  forms  it  is 
ellipsoidal.  In  the  bilateral  Nassellaria  it  is  elongate,  and  in  the 
Phaeodaria  spheroidal;  but  in  the  recently  discovered  spherical 
Thalassothamnidae  it  is  lobate  or  branched  (Fig.  10).  The 
consistency  of  the  central  capsule,  however,  is  not  that  usually 
associated  with  chitinoid  structures.  It  is  capable  of  extension, 
and  in  the  concentric  Sphaeroidea  and  Discoidea  it  is  lobate  and 
may  enclose  the  inner  shells  one  after  another.  In  the  helmet- 
shaped  Nassellaria  it  throws  out  lobes  through  the  basal  plate  of 
the  shells.  During  the  processes  of  fission  and  sporulation  the 
central  capsule  in  all  Radiolaria  becomes  more  or  less  completely 
dissolved  to  allow  of  the  separation  or  escape  of  the  endoplasmic 
contents.  These  phenomena  show  that  the  capsule  is  no  per- 


manent  excretion,  but  is  composed  of  a  substance  capable  of 
adaptation,  by  growth  or  dissolution,  to  changes  in  the  endoplasm. 

The  walls  of  this  structure  are  perforated  by  fine  pseudopodia 
that  connect  the  endoplasm  with  the  exterior  in  the  manner 
severally  characteristic  of  the  Peripylaria,  Monopylaria,  and 
Tripylaria  (pp.  102-9). 

The  evenly  distributed  or  segregated  pores  of  the  first  group 
admit  not  only  fine  plasmic  connections,  but  in  Acantharia  they 
also  transmit  axopodia  and  radial  spicules. 

The  single  pore-plate  of  the  Monopylaria,  which,  according  to 


Fio.  10. 

Cytodadus  spinosux.  x  10.  (After  Schroder  [38].)  One  of  the  Peripylaria,  to  show  the 
branched  central  capsule  (C.c),  the  radiate  single  spicule  (Sp),  and  the  voluminous  ectoplasm 
supported  by  the  spicular  rays.  It  has  been  recently  found  off  the  coast  of  Japan. 

Hertwig,  consists  of  perforated,  thickened  rods  of  capsular  mem- 
brane, is  not  thoroughly  understood.  In  most  Nassellaria  the 
pores  are,  of  course,  confined  to  one  plate-like  extremity  of  the 
.capsule,  but  they  may  be  evenly  distributed  over  the  basal  plate, 
confined  to  a  peripheral  zone,  or  to  three  circles,  which  in  Tridictyopus 
project  peripherally.  Associated  with  this  pore-plate  is  a  peculiar, 
.cone-like,  fibrillated  structure  which  projects  inwards  towards  the 
nucleus  (Fig.  5,  B,  p).  According  to  Hertwig  this  cone  is  an 
invagination  of  the  capsular  membrane,  and  the  fibrillae  are  con- 
tinuations of  those  that  pass  through  the  pore-plate,  on  their  way 
to  join  the  endoplasm  at  the  apex  of  the  cone.  Biitschli,  however, 


is  inclined  to  consider  the  cone  as  due  to  the  coalescence  of  axopodia 
somewhat  like  those  of  the  Acantharia  (9,  p.  439). 

The  central  capsule  of  the  Phaeodaria  possesses  well-marked 
characteristics  in  its  double  nature  and  the  presence  and  structure 
of  its  main  opening  or  astropyle  and  of  its  two  lateral  parapyles. 
The  former  consists  of  a  teat-like  operculum  apparently  striated  on 
the  inner  side  owing  to  the  septate  character  of  the  subjacent 
eridoplasm.  The  latter  are  made  up  of  an  inner  bulb  and  an  outer 
cone  which  opens  on  a  prominence.  The  endoplasm  under  the 
bulb  is  also  radially  grouped,  and  in  general  it  may  be  said,  as 
evidence  of  the  interchange  of  plasma  through  the  capsular  pores, 
that  the  endoplasm  in  their  neighbourhood  has  a  striated  character. 

The  morphological  character  of  the  central  capsule  is  a  moot 
point.  Most  authors,  following  Hertwig,  hold  it  to  be  comparable 
to  the  shell-membrane  of  a  Thecamoeba,  which,  however,  Dreyer 
considers  is  covered  by  ectoplasm  on  both  sides.  It  is  possible,  on 
the  other  hand,  that  the  capsule  is  a  basement  membrane  peculiar 
to  the  Radiolaria,  and  is  a  consequence  of  the  differentiation  of 
their  cytoplasm  in  relation  to  pelagic  life.  Until  its  development 
is  studied  the  question  cannot  be  satisfactorily  answered. 

Cytoplasm. — The  cytoplasm  of  Radiolaria,  though  one  and  con- 
tinuous, is  separable  anatomically  and  physiologically  into  intra- 
capsular  and  extracapsular  portions. 

Flotation  and  dispersal,  nutrition  and  stimulation  are  offices 
that  devolve  chiefly  upon  the  ectoplasm ;  storage  and  reproduction 
upon  the  endoplasm.  During  the  early  and  nutritive  stage  of  life 
the  ectoplasm  is  predominantly  active,  during  the  reproductive 
phase  the  endoplasm  is  solely  operative.  Continuity  of  structure 
and  community  of  function  are  expressed  by  an  interchange  of 
protoplasmic  and  metaplastic  granules  through  and  beyond  the 
capsular  wall. 

The  ectoplasm  consists  of  four  chief  layers  from  within  out- 
wards : — an  assimilative  zone  of  dense  protoplasm  around  the 
capsule,  a  thick  alveolar  layer  capable  of  secreting  gelatinous  and 
fluid  spheres,  an  enveloping  membrane  guarding  the  animal  from 
contact  with  its  environment,  and  beyond  this  a  fringe  of  radiating, 
contractile  pseudopodia.  This  great  development  is  primarily 
related  to  flotation.  From  Brandt's  researches  on  the  hydrostatic 
function  of  Radiolaria  it  is  clear  that  the  calymmal  gelatinous 
spheres  play  the  chief  part  of  this  office.  These  spheres  he  holds 
are  viscous  secretions  of  the  ectoplasm  and  absorb  water  from 
without  inwards.  The  specific  gravity  of  the  expressed  fluid 
is,  however,  such  as  to  point  to  water  saturated  with  carbonic  acid,, 
and  as  we  pass  from  the  inner  to  the  outer  zones  of  this  alveolar 
layer,  the  spheres  are  found  to  become  more  and  more  vacuolar, 
until  at  the  surface  they  are  so  tense  as  to  collapse  at  a  touch.. 


Brandt  therefore  considers  that  the  outer  pseudopodia  upon  con- 
tact with  certain  stimuli  (wave-motion  and  heat)  contract  and 
transmit  the  stimulus  to  the  subjacent  alveolar  protoplasm.  This 
in  turn  contracts  and  the  surface  vacuoles  collapse.  When  this 
process  has  been  continued  for  a  certain  time  the  specific  gravity  of 
the  animal  is  raised  and  a  slow  descent  follows.  Equilibrium 
is  again  established,  the  vacuoles  are  re-formed,  and  the  animal  rises 
again  to  the  surface. 

The  calymmal  spheres  do  not,  however,  monopolise  the  hydro- 
static function.  The  flotation  of  Radiolaria  is  determined  by 
extension  of  its  surface  as  well  as  by  the  lowering  of  its  specific 
gravity,  and  in  this  sustentative  adaptation  the  outer  pellicle 
and  the  skeleton  play  the  chief  role.  The  skeleton  of  the 
Acantharia  is  composed  of  a  radiating  series  of  tent-poles  upon 
which  the  ectoplasm  can  be  raised  and  tightened  by  the  elastic 
filaments  that  pull  up  the  baggy  ectoplasm,  which  upon  inflation 
by  vacuolar  water  expands,  and  so  raises  the  animal  to  a  higher 
zone  of  water ;  or  again  contracts,  followed  by  deflation  and  sinking 
of  the  whole  mechanism. 

Again,  in  Phaeodaria  we  have  a  still  more  elaborate  skeleton, 
the  appendicular  parts  of  which  are  related  to  the  formation  and 
support  of  the  ectoplastic  membrane.  In  an  impressive  variety  of 
sustentative  adaptations  the  ectoplasm  of  Eadiolaria  deposits  silicic 
acid  or  strontium  sulphate ;  and  the  attempt  now  being  made 
to  trace  a  correlation  between  the  variation  of  this  support, 
the  extent  and  thickness  of  the  outer  membrane,  and  the  density 
and  viscosity  of  various  tracts  of  water  inhabited  by  widely 
varying  forms,  has  already  met  with  some  success  (Hacker  [35]). 
Racial  forms  occur.  Aulacantha  scolymantha,  for  example,  only 
attains  a  diameter  of  2 '3  mm.  in  warm  surface  waters;  its  ecto- 
plastic membrane  is  soft  and  its  spicules  small  and  simple ;  whereas 
in  deep,  cold  water  (400-1000  metres)  it  reaches  7  mm.  and 
consists  of  a  much  tougher  envelope  supported  by  more  numerous 
spicules.  Circoporus  sexfuscinus  and  other  Phaeodaria  are  also 
dimorphic  and  exhibit  a  similar  differential  relation  to  the  surface 
and  abyssal  Avaters  in  which  they  occur. 

The  ectoplasm  rarely  contains  assimilates  or  other  inclusions. 
Oil -globules,  however,  occur  in  the  large  Collodaria ;  pigment 
(blue,  black,  brown,  or  red)  in  the  Thalassicollidae,  Sphaeroidea, 
Discoidea,  and  some  Acantharia ;  and  concretions  (probably 
proteid)  in  some  Thalassicollidae.  Yellow  cells  are  generally 
present  in  the  ectoplasm,  and  the  only  large  division  in  which  they 
are  unknown  is  that  of  the  Phaeodaria.  In  the  Acantharia, 
however,  they  occur  almost  constantly  in  the  endoplasm.  A 
further  account  of  these  cells  is  given  below. 

The  myonemes  are  peculiar  modifications  of  the  basal  ends  of 



certain  pseudopodia.  They  occur  exclusively  in  the  Acantharia 
Acanthometrida,  and  form  circular  groups  of  short,  rod-like  bodies 
clustered  round  each  of  the  radial  spicules  (Fig.  11).  Upon 
careful  examination  they  are  found  to  connect  the  ectoplasm  with 
the  pseudopodial  covering  of  the  spicule  and  to  possess  a  high 
degree  of  contractility.  Their  form  varies  accordingly.  When 
expanded  the  myonemes  appear  as  homogeneous  threads  '006  to 
•013  mm.  long.  When  contracted  they  not  only  become  shorter 
(•012-'02)  and  thicker,  but  exhibit  in  many  cases  a  very  distinct 
cross-striping.  They  are,  in  fact,  muscular  structures  comparable 



Fio.  11. 

Portion  of  a  living  specimen  of  Acanthometron  pellucidum,  one  of  the  Acantharia,  x900 
(after  Schewiakoff),  to  show  endoplasm  and  ectoplasm.  The  latter  consists  of  vacuolated 
cytoplasm  (E)  slung  up  to  the  rod  (S)  by  striated  myonemes  (.V),  which  are  inserted  into 
the  sheath  (Sh)  around  the  rod.  In  the  endoplasm  two  nuclei  (N)  and  zooxanthellae  (Z)  are 

with  the  contractile  fibrillae  of  Gregarines  and  Infusoria  (Schewia- 
koff [33]),  and  they  serve  to  raise  or  lower  the  hydrostatic,  ecto- 
plasmic  apparatus  of  these  Radiolaria,  and  so  to  facilitate  their 
ascent  or  descent. 

Another  cytoplasmic  modification  of  the  Acantharia  may  here 
be  mentioned,  namely,  the  axopodia.  They  consist  of  contractile 
pseudopodia  that  radiate  from  near  the  centre  of  the  endoplasm 
to  the  periphery  of  the  animal,  and  possess  an  axial  fibre  around 
which  an  unceasing  cyclosis  of  granules  takes  place.  These 
axopodia  differ  from  the  ordinary  pseudopodia  of  the  Acantharia 
not  only  in  their  deeper  origin  but  also  in  their  more  limited 


numbers  and  cyclical  arrangement,  and  they  resemble  the  peculiar 
pseudopodia  of  such  Heliozoa  as  Acanthocystis  in  all  points  except 
in  not  arising  from  a  centrosome.  The  peculiar  cytoplasmic 
threads  that  compose  the  so-called  flagellum  of  the  Discoidea  are 
also  in  all  probability  of  a  similar  nature.  This  flagellum  consists 
of  immobile  pseudopodia  fused  into  a  tapering  mass  which  projects 
freely  at  one  point  of  the  ectoplasm,  and  its  component  pseudo- 
podia, unlike  those  of  the  surrounding  calymma,  can  be  traced 
almost  to  the  centre  of  the  endoplasm.  They  appear  to  spring 
from  the  nucleus. 

A  peculiar  accumulation  occurs  in  the  extracapsulum  of  the 
Tripylaria,  to  which  the  name  phaeodium  is  given.  It  consists  of  a 
greenish  or  brownish  mass  concentrated  about  the  main  aperture  of 
the  central  capsule,  but  extends  around  the  capsule  for  a  third  of 
its  extent.  So  constant  and  characteristic  is  this  coloured  mass 
that  the  term  Phaeodaria  is  frequently  used  as  an  alternative  to 

The  constituents  of  the  phaeodium  in  Aulacantha  are  various — 
partly  extrinsic,  partly  intrinsic.  To  the  former  class  belong 
diatoms  and  the  debris  of  other  vegetal  organisms,  small  Radiolaria, 
and  Crustacea.  Most  of  these  undoubtedly  represent  food  material ; 
the  diatoms,  however,  may  be  symbiotic.  The  characteristic 
elements  of  the  phaeodium  are,  however,  the  phaeodellae,  which 
consist  of  spherical  or  ellipsoidal  corpuscles  which  vary  from  less 
than  1  ju,  to  20  /A  in  diameter.  These  corpuscles  occur  singly  or  in 
masses.  They  appear  homogeneous,  granular,  or  striated,  and  vary 
in  colour  from  a  hyaline  transparency  through  yellow-brown,  light 
and  dark  green,  to  black.  They  may  be  free  from  inclusions  or' 
contain  both  blackish  particles  of  varying  size  and  refractive 
granular  spheres  and  rods.  Towards  reagents  they  show  great 
refractoriness,  and  do  not  give  a  uric  acid  reaction  (Borgert). 

About  the  nature  of  these  phaeodellae,  opinion  has  long  been 
divided.  Haeckel  maintained  that  they  were  symbiotic  algae, 
other  zoologists  that  they  were  food  particles.  The  recent 
researches  of  Borgert  on  Aulacantha  have  suggested  another 
explanation.  Borgert  has  pointed  out  the  resemblance  of  certain 
granules  formed  in  the  endoplasm  in  the  neighbourhood  of  the 
astropyle  to  these  phaeodellae,  and  he  regards  these  corpuscles  as 
excretory  products  of  the  endoplasm  that  pass  out  through  the 
capsule  and  accumulate  in  the  surrounding  ectoplasm.  Recent 
work  on  the  brilliantly  coloured  algoid  structures  in  bathybial 
Challengeridae  and  Concharidae  have  shown  that  probably  both 
assimilation  and  excretion  are  carried  on  in  the  phaeodium  (36). 

Endoplasm. — The  endoplasm  is  the  site  of  storage  and  of 
reproductive  changes.  It  consists  of  a  granular  streaming 
cytoplasm  often  highly  vacuolated,  and  stratified  radially  and 


concentrically.  Imbedded  in  it  are  fatty  and  proteid  reserves, 
pigment,  crystalline  structures,  and  one  or  more  nuclei.  Oil- 
globules  are  generally  present  in  the  Spumellaria  and  Nassellaria, 
fatty  granules  in  the  Phaeodaria.  The  fat  may  be  colourless  or 
coloured  red,  yellow,  brown,  or  blue.  The  pigment  is  often 
closely  associated  with  the  oil-globules,  and  occurs  in  Thalassophysa 
on  the  peripheral  surface  of  the  globules.  The  crystalline 



«£fti?3&  <?l&fe    X'^A 

t\*S>r..  .''•:;         ''**£-jyLi&    s 


Portion  of  a  section  through  Planktonetla  atlantica,  Borg.,  one  of  the  Phaeodaria,  to  show 
the  phaeodium  (Ph)  tilling  up  the  ectoplasm  (Exo),  x  80.  (After  Fowler.)  Of.  Fig.  29  for  whole 
animal.  The  black  horizontal  line  is  the  "diaphragm"  or  ectocapsular  membrane,  that  is 
perforated  by  a  single  bundle  of  fibres  (Fibr),  if  not  also  by  the  smaller  similar  structures  (C). 
In  the  upper  ectoplasmic  half  of  the  figure  the  complex  phaeodium  is  seen  together  with 
branches  (Sp)  of  the  arms.  In  the  lower  half  the  delicate  central  capsule  (C.c.)  surrounds 
thejendoplasm  (End)  and  nucleus  (Nu),  and  is  itself  enclosed  in  a  shell  (Sh)  that  forms  a  float. 

structures  are  of  two  kinds :  (a)  small  whetstone -shaped  bodies 
probably  of  albuminous  nature ;  and  (b)  large  rhombic  structures 
indestructible  at  a  red  heat.  The  latter,  regarded  by  Brandt  as 
excretory,  are  in  all  probability  crystals  of  strontium  sulphate 
(Biitschli).  With  this  exception  the  contents  of  the  endoplasm 
may  be  regarded  as  reserve  material  destined  partly  for  the 
metabolism  of  the  animal  itself,  but  more  especially  for  the 
provisioning  of  the  spores,  into  which  the  endoplasm  breaks  up. 
Nucleus. — The  nucleus  of  the  Eadiolaria  is  still  very  im- 


perfectly  investigated,  and  the  following  statement  can  only  be 
regarded  as  a  provisional  account  of  its  coarser  features.  The 
two  chief  phases  of  life  are  signalised  by  distinctive  characters  in 
the  nucleoplasm.  In  the  vegetative  phase  it  consists  of  a  single 
large  vesicular  structure,  or  of  a  few  derived  from  this  by  mitotic 
division,  or  of  many  equivalent,  amitotically  produced,  small  nuclei. 
In  only  a  few  cases  are  chromidia  or  other  nuclear  derivatives  as 
yet  known  to  occur  in  this  phase  (Collosphaera,  SiphonospJiaera,  and 
Aulacantha),  and  there  is  no  separation  of  somatic  and  germinal 
nucleoplasm.  The  Radiolaria  are,  in  fact,  homokaryota.  Neverthe- 
less, at  the  advent  of  the  sporulating  phase,  the  nucleus  displays 
new  characters.  Either  it  becomes  differentiated  and  divides  into 
spore  nuclei ;  or  it  fragments  partly  into  chromidia  and  plasma,  which 
recombine  to  form  the  spore  nuclei,  and  partly  into  a  residue  which 
perishes  with  the  parental  exuviae.  In  this  process  we  can  detect 
a  certain  analogy  with  the  extrusion  of  nucleoplasm  during  the 
formation  of  the  spores  in  the  Heliozoa.  But  since  the  fate  of 
the  Radiolarian  spores  is  unknown,  a  just  comparison  of  the  two 
cases  is  at  present  impossible. 

The  nucleus  lies  wholly  in  the  endoplasm,  and  no  chromidia  or 
other  nuclear  products  have  yet  been  recognised  in  the  extra- 
capsulum  ;  but  the  axopodia  which  radiate  from  the  neighbourhood 
of  the  nucleus  in  certain  Nassellaria,  the  similar  fibrillae  that  run 
from  the  nucleus  outwards  to  form  the  flagellum  of  the  Discoidea, 
are  indications  of  the  paths  along  which  the  nucleus  probably  exerts 
its  influence  upon  the  ectoplasm,  and  vice  versa.  Further  evidence 
of  this  perinuclear  sphere  of  influence  is  found  in  the  apparently 
porous  character  of  the  nuclear  membrane  (Physematium,  Thalasso- 
lampe,  and  certain  Sphaeroidea)  and  the  radial  arrangement  of  its 
peripheral  plasma. 

The  characters  of  the  nucleus  vaiy  according  as  to  whether  it 
is  a  single  or  multiple  structure.  The  Collodaria,  Sphaeroidea, 
Nassellaria,  and  Phaeodaria  are  generally  mononuclear  :  the  Sphaero- 
zoa  and  Acantharia,  polynuclear  forms.  In  the  first  group  the 
nucleus  is  vesicular  and  differentiated  into  membrane,  sap,  chromatin, 
and  achromatin.  In  the  second  the  nuclei  are  without  a  distinct 
membrane,  and,  in  the  vegetative  stage,  homogeneous ;  their  origin 
from  the  spore  or  zygote  nucleus  has  been  traced  in  no  single 

One  or  two  special  forms  of  nucleus  may  be  referred  to. 
Among  the  Phaeodaria  the  majority  possess  a  nucleus  such  as  that 
shown  in  Fig.  15,  A,  together,  in  some  cases  (Aulacantha  scolymantha), 
with  chromatin  particles  scattered  through  the  endoplasm.  The 
Tuscaroridae,  however,  are  peculiar  in  having  (Figs.  13  and  30) 
an  elongate  nucleus,  with  a  loop  of  chromatin  enclosed  by  the 
nuclear  sap. 



Among  the  recently  discovered  and  reinvestigated  Spumel- 
larian  families,  Thalassothamnidae  and  Orosphaeridae,  a  totally 
new  type  of  nucleus  has  been  found  (Schroder  and  Hacker).  It 

consists  of  a  discoid  structure 
('1  mm.  diam.)  enveloped  by 
a  crenate  membrane,  and  is- 
composed  of  a  thin  cortical 
substance  and  a  central  mass- 
of  very  distinct  nucleoplasm, 
the  cortical  and  medullary 


substances  being  separated 
apparently  by  a  membrane 
(Fig.  14).  The  central 
nucleoplasm  contains  segre- 

The  central  capsule  and  nucleus  of    Tuscarora          ,     -,       £     i  i  i  ,  •      j 

nationalis.      (After    Borgert.)     As,    the    astropyle;  gated,      ICCbly       Chromatised 

Pa,  the  two  parapylae ;  Nu,  the  nucleus  with  its  p-rnnnlPo      imbedded      in      an 

chromatin  band  (Ch).     x  45.  &'a 

achromatic  matrix ;  the  cor- 
tical layer,  on  the  other  hand,  is  densely  chromatised.  The 
most  striking  feature  of  this  nucleus  is  perhaps  the  presence  of 
lenticular  bodies  at  intervals  along  the  junction  of  its  two  com- 
ponent layers,  or  in  one  genus  (Orosphaera)  just  outside  it.  These 
contain  large  compact  lumps  of  chromatin  imbedded  in  a  less- 
densely  staining  medium.  In  addition  to  this  central  nucleus, 
scattered,  chromatin-like  granules  (Fig.  1 4,  s)  occur  in  the  endoplasm, 
and  in  Orosphaera  these  peripheral  granules  are  unmistakable 
nuclei  of  a  simple  character. 

The  shape  and  size  of  the  nucleus  often  undergo  considerable 
change  during  growth.     It  remains  vesicular,  large,  and  spherical,. 

FIG.  14. 

Portion  of  a  section  through  the 
branched  central  capsule  of  Thalasso- 
thamnus.  (After  Hacker.)  The  centre 
of  the  capsule  with  its  nucleus  (N),  endo- 
plasm, and  inclusions  are  shown.  The 
stratified  concretions  (s)  stain  with 
haematoxylin,  arid  are  probably  chro- 
midial  structures.  In  Orosphaera  (a 
genus  which,  according  to  Hacker,  is 
closely  allied  to  Thalassothamnus)  these 
peripheral  nucleoplasmic  structures  are 
capable  of  division.  The  nucleus  (N) 
shows  well  the  division  into  crenate 
membrane,  peripheral  chromatic  layer, 
and  the  central,  mainly  achromatic  sub- 
stance in  which  groups  of  staining 
gran  tiles  occur.  Large  lenticular  bodies 
(/)  of  unknown  significance  occur  also. 

and  more  or  less  chromatised  in  the  Thalassicollidae  and' 
Physematiidae ;  but  in  the  Thalassophysidae  it  becomes  papillose, 
elongate,  and  serpentiform,  its  plasma  not  only  differentiates  into1 
inner  and  outer  substances,  but  the  spherical  or  thread -like: 


chromatin  accumulates  at  its  periphery  (Fig.  21,  A,  B).  In  the 
Sphaeroidea  the  nucleus  becomes  tubercular  and  follows  the  growth 
of  the  central  capsule,  as  this  encloses  successive  shells.  In  the 
simpler  forms  of  Nassellaria  the  vesicular  nucleus  remains  elliptical, 
but  in  the  Cyrtoidea,  in  which  it  lies  near  the  apex  of  the  shell,  it 
sends  lobes  (Fig.  4,  3)  into  the  adjoining  lappets. 

The  multinucleate  Radiolaria  offer  other  distinctive  characters. 
In  the  Sphaerozoa  each  individual  of  the  colony  possesses  a  gradu- 
ally increasing  number  of  structureless,  singly  refracting  nuclei, 
which  multiply  by  direct  fission,  and  have  rather  the  appearance  of 
nuclear  fragments  than  of  true  nuclei.  In  the  case  of  Collosphaera 
and  Siphonosphaera,  scattered  chromidia  (not  associated  as  far  as  is 
known  with  reproduction)  occur  as  well.  In  Acantharia  the  multiple 
nuclei  have  apparently  a  membrane  and  nucleoli,  the  multinucleate 
condition  is  constant,  and  the  distinction  drawn  by  Haeckel  between 
such  forms  and  oligo-  or  mononucleate  Acantharia  is  a  mistaken  one 
due  to  the  presence  of  a  parasitic  Amoebophrya  (Acinetaria),  which 
was  mistaken  for  a  nucleus  (Part  I.  p.  423,  Fig.  90).  More  difficult 
to  account  for  is  the  careful  description  by  Hertwig  of  a  temporary 
nuclear  condition  discovered  by  him  in  a  species  of  Acanthometron 
and  of  Amphilonche.  In  the  comparatively  few  nuclei  of  young 
specimens,  Hertwig  found  that  the  membrane  became  invaginated  on 
its  peripheral  side,  whilst  the  massive  nucleolus  showed  differentia- 
tion into  two  parts.  The  neck  of  the  infolded  membrane  became 
radiately  arranged,  and  its  deeper  portion  creased  into  circular 
folds  lying  one  over  another.  After  a  time  these  appearances 
vanished  and  the  nuclei  resumed  their  simple  spherical  form.  The 
phenomenon  may  be  one  of  internal  budding. 

The  advent  of  sporulation  is  prefaced  and  accompanied  by 
changes  in  the  nucleus.  These  changes,  however,  are  but  imper- 
fectly known  (p.  139).  Vesicular  nuclei  shrink,  their  membrane  gives 
way,  and  the  altered  chromatin  and  enclosed  nucleoplasm  either 
flows  out  into  the  endoplasm  or  gives  rise  to  a  nuclear  figure  and  then 
disperses  (see  above,  pp.  99-100,  for  Thalassicolla).  From  the  frag- 
mented material  spore-nuclei  arise.  By  the  former  method  isospore-, 
by  the  latter  heterospore-,  nuclei  develop.  In  the  Sphaerozoa,  how- 
ever, the  homogeneous  scattered  nuclei  remain  undifferentiated 
during  the  formation  of  isospores,  and  only  exhibit  a  change  from  a 
singly  to  a  doubly  refractive  property  ;  but  previous  to  the  develop- 
ment of  heterospores  their  nuclei  become  modified  into  chromatic 
and  achromatic  portions,  which  are  further  differentiated  in  the 
mega-  and  microspores. 

In  the  Phaeodaria  the  ellipsoidal  nucleus  is  usually  a  single 
large  structure,  but  two  or  three  nuclei  may  be  present.  It  con- 
sists (Fig.  14)  of  a  membrane  containing  a  linin  network.  The 
chromatin  is  massed  at  the  centre,  and  from  this  point  radiating 


strands,  threads,  and  lumps  run  outwards  towards  the  periphery. 
In  addition  to  these  chromatised  elements,  threads  and  granules  of 
another  substance,  the  so-called  paranuclein  of  Borgert  (18),  are 
present.  Nucleoli  are  absent. 

The  phenomena  of  nuclear  division  in  this  group  have  been 
carefully  studied  by  Borgert  (17,  18)  and  Karawiew  (16)  in 
Aulacantha  scolymantha,  but  only  mitotic  division  has  been  fully 
described.  Direct  division  of  the  nucleus  without  elongation  is 
known,  but  only  a  preliminary  account  has  as  yet  been  published. 
The  behaviour  of  the  nucleus  during  sporulation  is  unknown. 
Nuclear  mitosis  in  Aulacantha  exhibits  five  phases.  In  the  first 
or  spirem  stage,  the  linin  threads  form  a  dense  coil,  along  which 
the  chromatin  becomes  arranged  in  a  moniliform  fashion ;  a  few 
remnants,  together  with  the  paranuclein,  lie  scattered  through  the 
nucleoplasm.  The  coil  is  in  all  probability  never  a  continuous 
thread,  and  no  distinct  centrosomes  appear  at  this  or  any  subse- 
quent phase.  The  next  stage  consists  of  two  events.  The  threads 
of  chromatin  become  cut  up  into  varying  lengths,  and  split  longi- 
tudinally so  as  to  form  rows  of  chromatin  globules  on  either 
side  of  the  linin  threads.  The  second  event  is  the  condensation  of 
these  globules  into  thick  short  lengths  of  double  chromosomes. 
The  pairs  so  formed  are  unequal  in  size  and  different  in  form, 
some  being  spherical,  some  elongated  or  rod-like,  but  the  members 
of  a  pair  are  alike.  Amongst  these  the  paranuclein  granules  lie  in 
isolated  heaps.  The  next  or  third  stage  is  characterised  by  a 
second  longitudinal  splitting  of  the  chromosomes  in  a  plane  at 
right  angles  to  the  first.  The  fission  products  separate,  elongate, 
and  become  thinner  and  twisted,  leading  up  to  the  fourth  stage  or 
second  spirem  phase,  which  is  so  far  different  from  the  first  in  that 
the  chromatin  elements  are  obviously  discontinuous,  and  the  nucleus 
as  a  whole  has  now  become  flattened,  discoidal,  and  bent,  in  conse- 
quence of  the  loss  of  its  membrane,  so  that  it  presents,  in  side 
view,  a  somewhat  triangular  outline,  the  apex  directed  towards  the 
astropyle.  The  large  mass  of  chromosomes  is  now  organised  on 
either  side  of  a  median  transverse  plane  passing  at  right  angles  to 
the  flattened  nucleus.  The  position  of  this  plane  is  occupied  by  a 
mass  of  short  chromatin  elements  and  debris,  between  which  para- 
nuclein granules  occur.  The  chromosomes  are  aggregated  on  each 
side  of  this  central  mass,  which  prevents  them  from  being  continuous 
from  one  side  of  the  nucleus  to  the  other,  and  are  more  densely 
crowded  near  the  centre.  The  whole  flattened  structure  stretches 
out  until  on  the  aboral  side  it  touches  the  central  capsule.  The 
fifth  phase  is  signalised  by  the  appearance  of  the  equatorial  plate. 
The  origin  of  this  structure  has  not  been  described,  but  the 
chromosomes  now  arrange  themselves  in  close  relation  to  it,  and 
become  heaped  up  in  parallel  series,  though  still  maintaining  marked 



differences  of  length  and  thickness.      The  plate  becomes  twisted 
sigmoidally  and  divides  parallel    to  its  surface,  the  two  columns 



Fio.  15. 

Mitosis  in  Aulacantha  scolymantha.  (After  Borgert  [18].)  A,  central  capsule  and  resting 
nucleus  showing  distribution  of  chromatin.  B,  second  spirem  stage  showing  commencing 
separation  of  the  chromatin.  C,  portion  of  sigmoidally  curbed  nucleus  showing  the  equatorial 
plate,  and  the  chromosomes  definitely  arranged  about  the  middle  line.  D,  separation  of  the 
two  rows  of  chromosomes  and  of  the  two  daughter  plates  into  which  the  equatorial  plate  has 
divided.  E,  central  capsule  showing  the  withdrawal  of  the  daughter  plates  and  commencing 
reconstitution  of  the  nuclei.  A,  B,  and  E  x  150,  C  and  D  x  900. 

of    chromosomes  move  apart  and   organise    two   daughter   nuclei 
(Fig.  15). 



These  complex  mitotic  phenomena  offer  many  peculiarities,  some 
of  which  are  discussed  by  Borgert.  The  absence  of  a  spindle  and 
of  centrosomes,  the  double  splitting,  great  number  and  variety  of 
the  chromosomes,  the  peculiar  twisting  of  the  nucleus  and  equatorial 
plate,  and  the  two  spirem  stages  render  this  form  of  karyokinesis 
unique ;  and  in  spite  of  the  labour  which  has  been  bestowed  upon 
its  analysis,  several  points,  such  as  the  origin  and  fate  of  the  equa- 
torial membrane  and  the  formation  of  the  daughter  nuclei,  are  still 

Yellow  Cells. — Zooxanthellae  occur  commonly  in  the  ectoplasm  of 
Spumellaria  and  Nassellaria ;  in  the  endoplasm  of  Acantharia ;  and 


FIG.  16. 

land  2,  two  specimens  of  Collozoum  inerme,  showing  zooxanthellae  (Z)  in  the  ectoplasm,  xlOO. 
3,  4,  and  5  are  magnified  views  of  a  single  xanthella,  showing  its  escape  as  a  biflagellated 
organism  from  the  cyst  which  it  forms  during  the  palmella  state  ( x  330).  K,  the  nucleus  ; 
chr,  the  two  chroma tophores  ;  the  inclusions  are  hollow,  amyloid  grains.  (After  Brandt.) 

are  absent  from  the  Phaeodaria.  Their  occurrence  is  facultative 
and  not  absolutely  constant.  They  are  very  abundant  in  orders 
with  a  well-developed  calymma  such  as  the  Collodaria  (both  mono- 
zoic  and  polyzoic),  less  so  in  the  Sphaerellaria,  and  in  Physematiidae 
with  no  extracapsular  vacuoles,  and  are  absent  in  the  Discoidea. 
Similarly,  zooxanthellae  increase  in  number  with  the  increase  of  size 
of  the  animal  or  coenobium  in  which  they  occur.  Young  colonies  of 
Collozoum  up  to  50  or  100  members  contain  few  or  no  zooxanthellae, 
older  ones  become  impregnated  with  them. 

The  zooxanthellae  of  the  Spumellaria  are  similar  in  structure 
and  behaviour  to  those  of  Thalassicolla  (pp.  97-8).  They  are  usually 
spherical  organisms  with  a  single  apparently  homogeneous  nucleus, 
capable  of  assimilating  carbon  and  of  forming  sheaths  of  a  singly 


refractive  amyloid  substance  around  a  clear  centre.  In  the  Collodaria 
they  vary  from  '015  to  '025  mm.  in  diameter  ;  in  the  Sphaerellaria 
from  '005  to  '01  mm.  In  the  Nassellaria  the  zooxanthellae  are 
very  small  in  some  Cyrtoidea  (Eucecryphalus) ;  very  large  in  others 
(Eucyrtidium,  Dictyopodium).  A  cellulose  wall  is  present  and  en- 
closes cytoplasm  which  contains  two  chromatophores  impregnated 
by  chlorophyll  and  diatomin.  In  addition  to  the  scattered  hollow 
vesicular,  singly  refractive  structures  that  react  to  iodine  by  a 
violet  or  bluish-violet  tint,  other  doubly  refractory  granules  occur, 
and  these  are  unaffected  by  iodine.  After  the  death  of  the  ecto- 
plasm in  which  these  zooxanthellae  live,  they  pass  into  a  palmella 
stage  and  issue  as  biflagellated  organisms  upon  a  free  stage.  The 
structure  and  life-history  of  these  zooxanthellae  prove  that  they 
are  organisms  living  in  association  with  Eadiolaria,  but  it  is  not 
possible  to  assign  them  to  their  true  systematic  position.  Most 
authors,  following  Biitschli,  have  placed  them  in  the  Crypto- 
monadinae,  a  small  heterogeneous  group  of  simple  algae ;  but,  as 
Schaudinn  has  pointed  out  in  his  work  on  the  zooxanthellae  of 
Trichosphaerium  (42),  it  is  also  possible  that  these  organisms  have 
quite  other  affinities.  Brandt  (10a)  and  Klebs  (46)  have  drawn 
attention  to  the  similarity  between  the  flagellated  stage  of  the 
xanthellae  and  the  Peridinian  Exuviaella  marina.  Further  investiga- 
tion of  the  behaviour  of  these  yellow  cells  is  necessary  before  their 
position  can  be  accurately  denned. 

Yellow  Cells  of  Acantkaria. — The  xanthellae  of  the  Acantharia 
differ  in  many  ways  from  those  of  other  Radiolaria.  They  are 
mainly  intracapsular,  and  always  naked  cells.  In  some  families 
they  assume  a  spherical  form,  in  others  an  irregular  amoeboid  shape. 
These  cells  pass  by  easy  transitions  to  mere  heaps  of  pigment 
granules.  When  numerous  they  vary  in  size  from  '006  to  '008 
mm.  When  few  they  attain  a  much  larger  size,  '015  to  '03  mm. 
The  latter,  which  are  found  in  Acanthoniidae,  Lithopteridae,  and 
Amphilonchidae,  are  probably  the  largest  zooxanthellae  known.  In 
Acanthonia  tetracopa  and  other  members  of  the  same  family,  besides 
the  usual  intracapsular  mass  of  zooxanthellae,  a  few  occur  now  and 
then  in  the  extracapsulum.  In  Dorataspis  and  Actinomma  large 
amoeboid  zooxanthellae  occur  regularly  in  this  position.  These 
structures  are  almost  constant  in  Acantharia,  but  they  are  absent 
in  young  specimens  and  in  the  few  species  taken  in  deep  water. 

The  observations  of  Brandt  (lOrt)  on  the  finer  structure  of  the 
Acantharian  zooxanthellae  suggest  that  they  have  acquired  a  much 
closer  association  with  these  Radiolaria  than  have  those  of  Spumellaria 
with  their  host,  and  that  the  older  view  of  their  nature  was  nearer  to 
the  true  significance  of  the  association  than  the  modern  one  that 
regards  the  zooxanthellae  as  merely  immigrant  algae.  Haeckel  and 
Hertwig  regarded  them  as  pigment  cells  formed  by  the  segregation 



of  the  scattered  granules  and  vesicles  about  so  many  nucleated  centres- 
in  the  endoplasm,  and  therefore  as  integral  parts  of  the  Radiolarian, 
acting  the  part  of  storing  reserve  material.  Brandt  has  shown  that 
their  structure,  though  not  suggesting  this  view  of  their  origin,  serves 
to  explain  the  connection  between  the  pigment  granules,  pigmented 
granular  heaps,  and  definite  yellow  cells.  Starting  from  the  last, 
with  its  single  nucleus,  plates  of  diatomin,  numerous  amyloid  vesicles 
and  refractive  granules,  Brandt  finds  other  xanthellae  with  multiple 
minute  nuclei,  and  by  fragmentation  of  these  yellow  cells  he  accounts 
for  the  presence  of  the  isolated  yellow  granules,  each  of  which,  he 
affirms,  is  a  living  corpuscle  and  possesses  a  very  small  nucleus 
(lOa,  p.  237).  This  degeneration  of  the  zooxanthellar  nucleus  into  a 
heap  of  chromatin  granules,  associated  with  the  breaking  up  of  the 


Fid.  17. 

A-C,  yellow  cells  (zooxanthellae)  of  Acantharia.  (After  Brandt.)  A,  large  amoeboid  cell 
from  Acanthonia  tetracopa.  B,  C,  spindle-shaped  zooxanthellae  (A.  tetracopa).  D,  single  xan- 
thella  of  Thalassophysa  sanguinolenta,  to  show  its  cell-wall  (C.w),  hollow,  singly  refractive 
inclusions  that  stain  bluish  violet  with  iodine.  G,  doubly  refractive  granules  unaffected  by 
iodine,  x  1000.  . 

cell,  is  probably  not  to  be  explained  through  digestion  of  the  yellow 
cells  by  the  Acantharian,  but  as  a  consequence  of  the  intimate 
association  between  the  two  structures.  Unlike  the  zooxanthellae  of 
the  Spumellaria,  which  live,  divide,  and  sporulate  after  the  death 
and  dissemination  of  their  host,  those  of  the  Acantharia  lose  their 
power  of  independent  existence,  and  when  the  endoplasm  in  which 
they  occur  becomes  transformed  into  isospores  or  heterospores  they 
too  pass  into  these  spores  in  the  form  of  granules  and  starch 
grains.  Thus  the  flagellated  heterospores  of  Xipliacantha  alata 
(Fig.  26,  A)  contain  a  mass  of  yellow  granules,  besides  an  amyloid 
body  (staining  blue  with  iodine),  which  is  constantly  present  in  the 
iso-  and  heterospores  of  this  species.  It  is  therefore  possible  that 
the  yellow  cells  of  Acantharia  pass  from  mother  to  offspring,  and  it  is 
certain  that  amyloid  deposits  are  so  transmitted.  The  zooxanthellae 
of  Acantharia,  therefore,  once  they  have  entered  the  Radiolarian, 


never  leave  it.  They  become  assimilating  granules,  apparently 
incapable  of  independent  life,  and  are  transmitted  from  parent  to 
offspring.  In  the  former  conclusion  we  have  a  remarkable  parallel 
to  the  history  of  the  green  cells  (zoochlorellae)  in  Convoluta  roscoffensis 
(Keeble  and  Gamble  [41]). 

The  nature  of  these  interesting  zooxanthellae  is  not  satisfactorily 
settled,  but  the  scanty  evidence  points  to  affinities  quite  distinct 
from  those  of  the  other  Radiolaria.  In  the  absence  of  a  knowledge 
of  the  life-history,  Brandt's  view  is  as  likely  as  any  other,  but  it  is 
by  no  means  certain  that  all  the  Acantharian  zooxanthellae  are 
of  similar  parentage.  This  view  is  that  the  zooxanthellae  of 
Acanthoniidae  and  Dorataspidae  are  isolated  spindles  of  Labyrinthula 
vitellina  or  of  some  allied  species,  and  Brandt  (10a,  p.  239)  points 
out  the  agreement  between  the  two  structures  in  their  shape,  size, 
colouring,  and  nuclei. 

The  association  between  Eadiolaria  and  the  zooxanthellae  is 
usually  regarded  as  a  symbiosis,  i.e.  one  of  mutual  advantage.  It 
is,  however,  clear  from  the  foregoing  description  that  no  single 
formula  will  cover  the  important  facts — (1)  that  we  have  degrees  of 
intimacy  that  have  grown  up  between  the  two  organisms;  and  (2) 
that  the  last  term  in  the  series  of  association  is  one  to  which 
symbiosis  in  any  but  the  widest  sense  of  that  term  is  inapplicable. 

The  origin  of  the  association  is  probably  to  be  traced  to  the 
hunger  for  nitrogen  on  the  part  of  the  zooxanthellae ;  to  the 
minimal  quantity  of  inorganic  nitrogenous  food-stuffs  in  the  warmer 
seas  (Johnstone  [45]) ;  and  to  the  convergent  adaptation  of 
Radiolaria  and  zooxanthellae  to  life  at  or  near  the  surface  of  the 
ocean.  This  pelagic  and  insolated  station  is  attained  by  the 
Radiolaria  through  the  evolution  of  calymmal  structures  in  which 
nitrogen  is  in  all  probability  abundantly  present.  These  swarms 
of  inert  mucilaginous  Radiolarian  capsules  and  colonies  are  therefore 
in  every  way  suitable  media  for  the  nutrition  of  the  zooxanthellae. 
Attracted  in  all  probability  chemotactically  by  the  nitrogenous 
stores  in  the  mucilage,  the  zooxanthellae  enter  the  ectoplasm  and 
then  divide  and  assimilate.  Protected  by  their  cellulose  envelope, 
they  can  at  first  resist  the  digestive  enzymes  of  their  host; 
ultimately,  however,  their  nucleus  becomes  degenerate,  and  with 
this  change  the  protective  wall,  whose  formation  it  governs,  becomes 
weakened.  In  this  way  some  of  the  daughter-cells  of  the  primary 
zooxanthellae  become  food  for  their  host  (Famintzin).  The 
Radiolarian,  which  in  its  early  stages  fed  on  Peridinians,  Infusoria, 
and  small  Crustacea,  ceases  to  ingest  solid  food  and  relies  upon  the 
reserves  it  has  accumulated  or  upon  the  secondary  xanthellae  for 
its  supplies.  Meanwhile,  its  nitrogenous  metabolism,  and  possibly 
its  intramolecular  respiration,  is  maintained  by  the  xanthellae, 
which  are  removing  the  waste  nitrogenous  substances.  In  confirma- 



tion  of  this  statement  reference  may  be  made  to  the  Phaeodaria. 
This  group  of  Radiolaria  possesses  no  zooxanthellae,  and  might 
therefore  be  expected  to  show  some  accumulation  of  excretory 
granules.  This  appears  to  be  the  case,  for  the  complex  phaeodium 
is  made  up  of  refractory,  insoluble  vesicles  which  are  generally 
held  to  be  excretory  substances.  The  association  of  diatoms  with 
Radiolaria  has  probably  a  similar  significance. 

Finally,  when  the  endoplasm  sporulates  the  dying  ectoplasm 
serves  as  a  medium  in  which  the  zooxanthellae  rapidly  divide  and 
issue  as  naked  biflagellated  spores  upon  a  new,  free  existence.  In 
the  case  of  the  Acantharia,  which  are  also  mainly  epiplanktonic 
or  surface  organisms,  the  zooxanthellae  are  naked  cells,  almost 
exclusively  confined  to  the  central  portion  of  the  Radiolarian. 
Whether  they  develop  from  antecedent  zooxanthellae  that  occur 
in  the  spores  of  Acantharia  or  infect  it  from  sea-water,  or  whether 
both  modes  of  origin  obtain,  is  at  present  unknown.  The  apparent 
absence  of  xanthellae  from  young  Acantharia  makes  the  first  sugges- 
tion unlikely.  Within  the  central  capsule  they  divide,  multiply, 
and  assimilate.  Certain  of  them  fragment  into  particles,  the 
process  being  initiated  by  nuclear  fragmentation,  so  that  the 
zooxanthellae  are  no  longer  cells  but  mere  chromatised,  pigmented 
corpuscles,  associated  with  free  granules  of  starch  or  amyloid 
substances.  There  is  no  evidence  to  show  whether  in  this  or  in 
the  earlier  coherent  stage  the  xanthellae  are  digested  by  the 
Acantharian.  They  become  in  the  last  event  mere  assimilative 
corpuscles,  and  when  the  endoplasm  sporulates  the  whole  of  the 
zooxanthellae,  with  their  associated  starch,  pass  into  the  bodies  of 
the  flagellated  spores,  and  are  probably  used  up  as  food  by  the 
developing  zygote.  Throughout  this  series  we  see  that,  in  opposi- 
tion to  the  idea  of  mutual  benefit,  the  animal  is  the  predominant 
partner.  The  association  is  one  beginning  with  myxophytism  and 
leading  to  a  case  of  parasitism,  in  which  the  zooxanthellae  are  the 
host  and  the  Radiolarian  the  parasite. 

Skeleton. — The  skeleton  of  the  Radiolaria  has  developed  in  each 
of  the  great  sub-classes  into  a  complexity  of  form  and  variety  of 
detail  that  are  found  in  no  other  group  of  animals.  So  characteristic 
are  the  skeletal  products  that  it  is  usually  possible  from  them  alone 
to  recognise  broadly  the  systematic  position  of  the  organism  that 
produced  them.  So  complex  and  diverse  a  tracery  seems  utterly 
beyond  the  needs  of  simple  Protozoa  living  under  apparently  similar 
conditions  of  pelagic  life ;  and  though  attempts  have  been  made  to 
explain  this  manifold  skeletal  development  in  terms  of  cytoplasmic 
structure,  its  variety  still  evades  a  biological  treatment.  Recent 
investigation  has,  however,  done  something  to  reduce  this  variety 
to  a  few  plans,  and  to  attach  a  biological  meaning  to  some  of  its 
elaborations.  These  results  justify  the  hope  that,  as  we  come  to 


regard  the  skeleton  as  a  response  to  the  varying  media,  stresses, 
and  strains  that  fall  upon  the  cytoplasm  from  within  and  from 
without,  that  then  its  utilitarian  character  Avill  be  more  completely 
recognised,  and  its  variety  found  to  be  explicable  in  terms  of  com- 
position, mode  of  deposition,  and  the  need  of  response  to  widely 
varying  combinations  of  stimuli  that  occur  in  the  apparently  mono- 
tonous sea.  Two  very  different  substances  compose  the  greater 
part,  and  probably  the  whole,  of  these  skeletal  structures.  In  the 
Spumellaria  and  Nassellaria  pure  silica  is  present ;  in  the  Phaeodaria 
the  silex  is  mixed  with  organic  substance ;  but  in  the  Acantharia 
a  substance  is  present  which,  from  the  time  when  it  was  first 
described  by  Johannes  Miiller  to  the  present,  has  given  rise  to 
differences  of  interpretation.  Miiller,  relying  on  the  indestructible 
nature  of  the  Acantharian  skeleton  when  heated,  regarded  it  as 
siliceous.  Haeckel  found  that  it  was  apparently  destroyed  by  heat, 
and  regarded  it  in  the  main  as  an  organic  horny  substance  which 
he  called  acanthin.  Schewiakoff  (33)  tested  its  properties  and 
attempted  a  quantitative  analysis,  the  result  of  which  went  to  show 
that  the  so-called  acanthin  was  a  complex  silicate.  Quite  recently 
Biitschli  (39)  has  rein vesti gated  the  skeleton  of  Antarctic  and  of 
fiome  Mediterranean  Acantharia,  and  has  proved  that  in  these 
cases  it  is  composed  of  strontium  sulphate. 

The  diverse  forms  of  Radiolarian  skeletons  are  largely  founded 
upon  developments  of  scattered  aciculate  and  tetrahedral  spicules. 
Dreyer  has  indeed  attempted  to  trace  the  evolution  of  the  skeleton 
(1)  in  the  Acantharia  to  an  axopodial  type  derived  from  the 
hardening  of  the  axis  that  runs  down  the  peculiar  radiating 
pseudopodia  of  this  sub-class ;  and  (2)  in  other  Radiolaria  to  the 
modifications  of  a  tetrad  spicule,  which  in  turn  he  traces  to  the 
deposition  of  silica  at  the  intersecting  planes  of  adjacent  cyto- 
plasmic  vacuoles  or  alveoles ;  but  the  absence  of  a  knowledge  of 
the  development  of  the  skeleton  rendered  this  attempt  suggestive 
rather  than  convincing,  and  there  are  many  forms  of  skeleton 
which  it  is  difficult  to  assign  to  any  conceivable  modification  of  the 
tetrahedral  type.  In  the  present  state  of  our  knowledge  it  must 
be  admitted  that  the  vacuolated  cytoplasm  has  the  power  of 
•depositing  its  silica  in  the  form  of  perforate  or  imperforate  shells, 
plates,  and  processes,  so  that  in  addition  to  the  spicules  there  is 
often  a  great  development  of  siliceous  matter,  the  form  of  which 
cannot  be  referred  to  the  alveolar  structure  of  protoplasm. 

In  form  as  in  composition  the  skeleton  of  the  Acantharia  is 
sharply  marked  off  from  that  of  other  Radiolaria.  With  few 
exceptions,  it  consists  of  twenty  rods  united  in  various  ways  :  (1)  by 
opposition  and  also  by  adcentral  processes ;  (2)  by  fusion  of  all  or 
of  opposite  pairs,  at  the  centre  of  the  endoplasm.  These  radii  are 
.disposed  so  as  to  emerge  from  the  spherical  cytoplasm  along  five 



circles,  which  may  be  compared  to  the  equatorial,  the  two  circum- 
polar,  and  the  two  tropical  circles  of  the  globe  (Muller's  law).  In 
a  few  cases  two  radii  mark  the  vertical  axis,  and  the  other  eighteen 
are  disposed  in  three  circles — an  equatorial  one,  and  the  other  two 
respectively  45°  above  and  below  it  (Brandt's  law) ;  whilst  in  the 
apparently  primitive  Astrolophidae  the  spines  vary  in  number  and 

; — AX. 

Fio.  18. 

Acanthonia  tetracopa  in  its  two  extreme  phases  of  expansion  and  contraction,  one  half  of  the- 
animal  being  drawn  in  each  case.  The  relation  of  the  myonemes  to  the  ectoplasm,  and  their 
insertion  into  sheaths  around  the  radial  spines,  is  also  seen  (cf.  Fig.  11).  The  full  number  (20) 
of  spines  is  not  indicated.  (After  Schewiakoff.)  x  170. 

possess  no  regular  arrangement  beyond  their  radial  disposition. 
This  loose  order  is  repeated  in  the  early  development  of  the  Acan- 
thoniidae.  The  young  of  this  family  possess  ten  loose  rods  arranged 
crosswise,  which  subsequently  become  divided  at  the  centre  of 
the  capsule  into  the  typical  twenty  radii.  In  the  Acanthochias- 
midae  the  distal  portion  of  each  radius  gives  off  tangential  processes- 
which  unite  with  those  of  adjoining  spines  and  so  form  a  perforated 


shell.  By  repetition  of  the  process  farther  along  the  radii  a  second 
and  succeeding  concentric  shell  may  arise,  In  the  most  modified 
case  (Sphaerocapsidae)  the  lattice  alone  is  present,  but  the  place  of 
the  radii  is  shown  by  twenty  large  pores  distributed  according  to 
Muller's  law. 

In  the  Spumellaria  the  skeleton  is  either  absent,  spicular,  or 
shelly.  Both  spicules  and  perforated  shells  are  often  present 
simultaneously,  and  have  evidently  developed  independently  in 
two  of  the  main  subdivisions — Sphaerozoa  and  Sphaerellaria. 
But  whilst  in  the  former  the  shell  is  single,  in  the  latter  it  often 
becomes  multiple,  interconnected  by  radial  bars,  and  flowers  out 
into  a  wealth  of  appendicular  growths  that  characterise  this  vast 
group,  which  numbers  two-fifths  of  the  known  Kadiolaria.  The 
Sphaeroidea  retain  the  homaxonial  form ;  the  Discoidea  have  only 
the  first  or  first  and  second  chambers  spherical,  and  farther  outwards 
become  flattened  and  often  cruciform,  the  arms  of  the  cross  being 
frequently  divided  into  a  large  number  of  chambers,  into  all  of  which 
the  endoplasm  and  its  associated  pigmented  oil-globules  may  pass. 
Other  modifications  are  mentioned  in  the  conspectus  (pp.  144-145). 
In  the  Nassellaria,  the  Kadiolarian  skeleton  develops  into  its  richest 
expression  of  geometric  form.  Its  simplest  types  consist  of  a  single 
or  multiple  ring  and  of  a  tripod  or  tetrad  (see  Fig.  5),  and  from 
these  a  helmet-shaped  perforated  shell  has  arisen,  apparently  by 
lateral  extensions  of  the  simpler  plan.  Such  a  cephalis  may  be 
simple  or  divided  both  sagittally  and  transversely  by  one  or  more 
constrictions,  and  in  exceptional  cases  a  spherical  shell  may  be 
developed.  The  most  interesting  feature  of  this  group  is  that  the 
whole  of  its  variety  can  be  traced  fairly  confidently  to  the  modifi- 
cations of  a  single  element  which  Biitsclili  (8)  believes  to  be  a 
ring  and  Dreyer  (15)  a  tetrad  spicule. 

The  skeleton  of  the  Phaeodaria  has  followed  another  line  of 
evolution.  It  consists  essentially  of  minute  aciculate  spicules 
imbedded  in  a  gelatinous  matrix.  Between  these  a  jelly-like 
substance  is  secreted  ;  the  inner  layer  of  this  matrix  becomes  silici- 
fied  to  form  a  tube,  the  cavity  of  which  is  often  subdivided  by  one 
or  more  septa ;  or  the  intermediate  jelly  may  also  become  silicified 
as  a  porous  plate  or  shell  of  porcellanous  texture.  Commencing 
with  the  Phaeocystina,  in  which  the  skeleton  is  absent  or  composed 
merely  of  isolated  radial  and  tangential  spicules,  the  formation  of  a 
lattice-shell  has  come  about  in  several  ways.  The  simplest  mode  is 
that  seen  in  the  Aulosphaeridae,  in  which  the  tangential  spicules 
unite  to  form  an  open  peripheral  network.  To  this  a  second  shell 
may  be  added  by  the  formation  of  a  reticulum  immediately  outside 
the  central  capsule  (Cannosphaeridae).  If  the  outer  shell  is  absent, 
a  condition  found  in  the  Castanellidae  is  obtained.  In  these 
Phaeodaria  the  single  shell  is  composed  of  two  conjoined  membranes 


imbedded  in  a  porcellanous  impregnation  throughout  which  minute 
aciculate  spicules  occur.  It  is  provided  with  an  oral  opening  on  the 
end  of  a  projecting  and  often  spiny  peristome.  Again,  this  inner  shell 
may  assume  a  bi valvular  form  (Fig.  32),  and  then  carries  a  number 
of  complex  appendages.  Some  of  these  are  branching  hollow 
species,  terminating  in  anchor-like  expansions ;  others  constitute  the 
"galea"  and  "rhizocanna"  (see  Fig.  32,  p.  151). 

Biological  Significance  of  the  Skeleton. — The  results  of  recent 
investigation  point  to  the  conclusion  that  the  chief  skeletal  function 
is  a  hydrostatic  one  and  is  effected  by  stretching  or  folding  the 
superficial  ectoplasm.  The  older  conception  of  the  skeleton  as 
projecting  freely  beyond  the  cytoplasm  has  been  shown  to  be  a 
mistaken  one  in  many  instances,  and  it  is  probable  that  the  skeleton 
is  during  life  covered  by  the  outermost  delicate  plasmic  layer 
in  all  Radiolaria.  Between  the  characters  of  this  layer  and  the 
development  of  the  supporting  rods  a  definite  relation  holds  for 
certain  forms.  A  few  widely  varying  Radiolaria  are  dimorphic,  a 
small  pelagic  variety  and  a  larger  abyssal  form  being  readily  and 
apparently  rightly  distinguishable  (Aulacantha  scolymantha,  Auloscena 
and  Sagosphaera-species).  In  these  cases  the  surface-form  possesses 
a  delicate  ectoplasmic  layer,  and  the  supporting  rods  are  simpler 
and  shorter,  whereas  in  the  bathybial  variety  the  outermost 
cytoplasm  is  dense,  more  voluminous,  and  usually  more  stiffly  sup- 
ported by  verticillate  skeletal  projections.  The  graceful  and 
elaborate  skeletal  appendages  of  other  Phaeodaria  are  probably  to 
be  explained  not  as  a  means  of  catching  food,  but  as  a  support  for 
the  ectoplasm ;  and  the  whole  plan  and  construction  of  the  tubular 
skeleton  in  these  forms  is  no  doubt  related  intimately  to  the 
pressures  that  fall  upon  this  limiting  layer. 

In  connection  with  this  sustentative  function  of  the  Phaeodarian 
skeleton,  the  mode  of  formation  of  its  tubular  systems  offers  some 
features  of  special  interest.  The  most  general  mode  is  that  indi- 
cated at  the  close  of  the  last  section  (p.  133),  and  in  this  method 
minute  needle-like  spicules  form  the  centre  around  which  tubular 
developments  of  silica  take  place.  But  in  addition  to  this  intrinsic 
centre,  many  Phaeodaria  have  adopted  extrinsic  objects,  and  around 
these  as  catalysators,  the  tubular  silica  is  deposited.  Like  other 
Radiolaria,  but  to  a  greater  extent,  the  Phaeodaria  ingest  quantities 
of  foreign  bodies,  with  which  their  phaeodium  is  distended.  Amongst 
these  ingesta,  diatoms  and  Radiolarian  skeletons  are  abundant. 
From  Phaeodaria,  in  which  such  gatherings  are  casual,  we  can  trace 
a  series  leading  to  forms  in  which  diatom-selection  becomes  a  regular 
habit,  associated  directly  with  the  formation  of  a  radial  skeleton. 
Thus  Aulographis  pandora  and  Auloceros  arborescens  from  the  Atlantic 
and  Indian  Oceans  contain  in  their  phaeodia  frustules  of  lihizosolenia, 
and  spicules  of  many  species  of  Aulacanthids  picked  up  apparently  in 



a  casual  manner,  and  probably  serving  to  increase  the  extent  of 
exposed  surface.  Cannosphaera  from  Antarctic  seas  .possesses  a 
hollow  skeleton  the  tubes  of  which  are  almost  filled  with  masses  of 
the  diatom  Corethron ;  and  finally,  in  Aulokleptes  (Fig  19)  and 
Aulodendron  the  diatoms  are  planted  radially  in  the  ectoplasm, 
surrounded  by  a  mucilage,  and 
finally  incorpoi'ated  into  the  walls 
of  a  hollow  radial  tube,  the  lamellae 
of  which  are  laid  down  from  within 
outwards,  and  the  top  of  which  is 
moulded  into  the  form  severally 
characteristic  of  the  species  (Immer- 
mann,  Hacker). 

The  biological  significance  of 
the  varieties  of  Nassellarian  spicule 
and  of  the  scattered  Spumellarian 
spicules  and  lattice  -  shells  is  at 
present  quite  obscure,  but  the 
skeleton  of  the  Acantharia  offers 
perhaps  the  clearest  case  of  func- 
tional significance  to  be  found  in 
the  whole  group  (Dreyer,  Brandt, 
Popowsky).  The  twenty  radial 
spokes  of  the  Acanthometrea  serve 
as  so  many  tent-poles  for  the  in- 
sertion of  the  myonemes  (Figs.  11 
.and  18)  that  hoist  the  calymmal 
cones.  This  action,  combined  with  absorption  of  water  into  the 
vacuoles,  causes  a  swelling  of  the  cytoplasm  and  brings  the 
animal  towards  the  surface ;  whereas  relaxation  of  the  myonemes 
and  contraction  of  the  calymma  depresses  it  beyond  the  reach  of 
wave-action.  The  skeleton  of  this  subdivision  is,  however,  related 
to  hydrostatic  ends  in  another  way.  The  definite  arrangement  of 
the  twenty  spines  according  to  what  is  known  as  Miiller's  law 
(p.  132)  has  recently  been  correlated  with  flotation  and  dispersal. 
Brandt  has  shown  that  the  distribution  of  the  radii  in  five  alternate 
and  superposed  circles,  each  of  four  spicules,  is  such  as  to  expose 
them  freely  and  without  overlapping  to  the  viscosity  and  resistance 
of  the  water.  The  absence  of  vertical  or  axial  spines  is  also  intel- 
ligible, since  they  would  increase  the  weight  of  the  body  without 
giving  additional  buoyancy.  Moreover,  the  shape  as  well  as  the 
arrangement  of  the  spines  assist  the  Acantharia  in  their  flotation 
and  dispersal.  Like  all  other  Radiolaria,  these  are  dependent  on 
currents  and  drift  for  their  dissemination.  In  order  to  utilise  this 
horizontal  force,  the  radial  spokes  are  frequently  provided  with  four 
flanges  or  blades,  which  serve  the  double  purpose  of  encountering 

Fio.  10. 

Spicule  from  Aulokleptes  floscvlus  formed 
around  a  dividing  diatom  Rhizosoknia. 
(After  Immermann.)  x  55. 


sustentative  and  propulsive  forces.  When  these  blades  are  wanting 
and  the  spines  are  merely  flattened,  they  are  set  in  each  of  the 
three  circles,  so  as  to  turn  the  flat  edge  somewhat  differently  to  the 
water,  the  equatorial  ones  lying  flat  on  the  water,  the  tropical  ones 
turned  half  over,  and  the  polar  spines  set  on  edge.  By  this  means 
the  amount  of  resistance  to  the  water  in  every  direction  is  increased. 
The  exceptionally  wide  distribution  of  the  Acanthometrida  is  some 
confirmation  of  these  deductions. 

Fission — Reproduction. — The  phenomena  of  multiplication  and  of 
reproduction  are  still  imperfectly  known.  Binary  or  multiple 
fission  occurs  in  some  Spumellaria,  Acanthometrida,  and  Phaeodaria. 
Gemmation  is  a  rarer  mode.  It  produces  the  extracapsular  bodies 
of  the  Spliaerozoidae,  and  is  found  in  one  species  of  the  Acantharia 
and  of  the  Phaeodaria  respectively.  The  development  of  zoospores 
is  a  general  phenomenon,  but  has  been  followed  in  detail  only  in  a 
few  cases.  Plastogamy  is  unknown. 

The  mode  of  increase  by  fission  is  probably  restricted  to  those 
Radiolaria  which  have  no  spicules  or  a  lax  and  osculate  skeleton. 
Binary  fission  occurs  in  the  Thalassicollidae,  some  Acanthometridae, 
and  in  two  families  of  Phaeodaria.  Division  both  of  the  Sphaero- 
zoid  colony  and  of  its  component  individuals  takes  place  at  intervals. 
Multiple  fission  occurs  in  the  Thalassophysidae.  The  process  is 
usually  initiated  by  changes  in  the  endoplasm  and  nucleus,  and  a 
long  interval  may  follow  before  any  corresponding  alterations  occur 
in  the  ectoplasm  (Phaeodaria). 

In  the  Acanthometrida  (Acanthoniidae)  binary,  quatenary, 
and  multiple  fission  are  said  to  occur  (Popowsky).  The  former 
process  is  illustrated  in  Fig.  20.  The  skeletal  rods  separate  at 
their  central  ends  into  two  bundles,  the  nuclei  segregate  into  two 
groups,  the  central  capsule  divides,  and  ultimately  fission  takes 
place.  The  fission  -  products  are,  however,  asymmetrical,  and 
Fig.  20  shows  how  the  new  radii  are  developed  and  how  the  rods 
are  swung  into  position,  probably  by  contraction  of  the  myonemes 
inserted  into  them,  until  the  whole  arrangement  is  brought  into 
conformity  with  Muller's  law. 

Fission  in  the  Phaeodaria  is  carried  out  in  several  ways. 
Aulacantha  scolymantha  is  the  best-known  example  of  the  direct 
process.  In  this  Radiolarian  the  large  single  nucleus  divides  either 
by  mitosis  or  amitotically ;  the  endoplasm  segregates  round  the 
daughter  nuclei ;  the  central  capsule,  after  disappearing  for  a  time, 
re-forms  about  the  two  masses.  Lastly,  the  phaeodial  complex,  the 
calymma  and  spicular  skeleton  are  subdivided  each  into  two  groups, 
and  the  whole  organism  divides  into  two.  In  the  Phaeodaria, 
which  possess  a  shell,  one  or  more  modifications  of  the  process  are 
found.  The  helmet-shaped  Challengeridae,  for  example,  undergo 
fission  within  the  shell.  One  half  of  the  organism  now  escapes 



through    the    oral   aperture   and  develops    into    a    new  individual 
{Borgert  [2 la],  p.  100). 

The   most  remarkable  case  of  multiple   fission    occurs  in  the 
Thalassophysidae,  and  constitutes  the  only  known  means  of  increase 

FIG.  20. 

Illustrating  fission  in  the  Acanthometrida.  (After  Popowsky.)  A,  Acanthometrnn  bifidum 
about  to  divide.  The  spicules  are  arranged  in  two  bundles.  The  central  capsule  has  dis- 
.appeared.  The  ectoplasm  is  a  mere  hyaline  border  round  the  granular  endoplasm,  x!50. 
1$,  lission  of  Amphilonche  atlantica.  My,  the  myonemes,  xloO.  C,  regeneration  of  the  same  ; 
formation  of  a  directive  large  spicule,  x  150.  D,  spicules  reassuming  their  characteristic 
arrangement,  x  150. 

in  this  family.  Fig.  21  illustrates  the  process,  which  has  been 
investigated  by  Brandt  (25).  The  central  capsule  and  nucleus 
become  irregular-branching,  vermicular,  or  radiating  structures. 
The  oil-globules  and  their  associated  pigment  granules  become  dis- 
seminated through  the  endoplasm.  Then  the  nucleoplasm  breaks 
tip  into  a  vast  number  of  minute  homogeneous  corpuscles,  followed 



by  rapid  division  of  the  capsule  and  endoplasm.  The  ectoplasm 
fragments  and  the  products  are  disseminated  through  the  water. 
Each  minute  product  consists  of  several  nuclei  lying  in  a  pigmented, 
oily  fragment  of  endoplasm  and  supported  by  a  portion  of  the 
original  ectoplasm.  The  further  history  of  these  bodies  is  unfortu- 
nately not  known. 


FIG.  21. 

Multiple  fission  in  Thalassophysidae.  (After  Brandt.)  A,  central  capsule  and  nucleus  of 
Th.  spiculosa,  x  40.  B,  section  of  the  nucleus  to  show  the  two  zones  of  nucleoplasm  and  the 
vermicular  nucleoli  in  the  outer  layer,  x  66.  C,  Th.  pelagiea  about  to  divide  ;  the  nucleus  has 
undergone  fragmentation.  D,  multiple  fission  of  the  central  capsule  of  Th.  pelagica.  E, 
enlarged  view  of  a  portion  of  the  same,  x  200.  F,  stained  portion  of  capsule  of  the  same  ta 
show  nuclei  before  fragmentation  of  the  capsule.  G,  division  of  central  capsule  of  Th.  sanguino- 
lenta,  x  7.  C.e,  central  capsule ;  N,  nucleus  of  vegetative  individual ;  NI,  nucleus  of  frag- 
menting individual ;  On,  In,  outer  and  inner  zones  of  endoplasm. 

The  separation  of  a  portion  of  the  Radiolarian  organism  as  a- 
bud  is  a  rare  phenomenon,  of  which  the  "  extracapsular  bodies  "  of 
the  Sphaerozoidae  offer  the  best  example.  These  structures  occur 
in  small  colonies  of  Cullozoum  inerme,  C.  radiosum,  C.  fulmim,  and  of 
Sphaerozoum  neapolitanum.  They  consist  of  a  lobate,  highly  refrac- 
tive, cytoplasmic  mass,  containing  a  group  of  modified  nuclei 
ranged  about  a  grape-shaped  mass  of  fat,  and  are  loosely  attached 
to  the  colonial  jelly  (Fig.  22).  These  extracapsular  bodies  are 
budded  off  from  the  endoplasm  of  certain  members  of  the  colony  in 
which  they  occur,  and  are  at  first  uninuclear.  According  to  Brandt's- 



account  (10)  these  bodies  have  a  twofold  significance.  Either 
they  become  additional  members  of  the  parental  colony  and  develop 
central  capsules,  or  they  become  megaspores  and  the  small  parental 
endoplasm  develops  microspores.  In  his  later  work  Brandt  lays 
additional  stress  on  the  latter  fate.  He  has  not  only  seen  the  bean- 
shaped  active  megaspores  formed  by  the  extracapsular  bodies,  but 
(26,  p.  264)  also  the  mass  of  microspores  formed  by  the  small 
capsules  which  had  budded  off  these  bodies :  a  proterogynous 
arrangement.  It  should  be  added  that  Brandt  affirms  very  strongly 
the  juvenile  nature  of  these  small  budding  colonies ;  whilst  Famintzin, 

FIG.  22. 

Collozoum  sp.    Portion  of  a  colony  showing  extracapsular  bodies  (E.C). 
x  100.    (After  Brandt.) 

working  in  the  same  locality,  asserts  that  their  small  size  is  due  to 
fission  of  full-grown  coenobia  (13). 

Spore  -  Formation. — Flagellated  spores  occur  in  the  four  main 
divisions  of  the  Radiolaria,  but  their  exact  nature  is  only  known  in 
some  Collodaria  and  some  Acantharia,  and  it  is  in  the  former  order 
that  their  formation  has  been  traced.  The  process  is  described  for 
Thalassicotta  on  pp.  99-102. 

Isospores.  —  The  development  of  isospores  in  the  Sphaerozoa 
takes  place  in  colonies  distinct  from  those  that  produce  heterospores. 
After  a  vegetative  life  of  several  months  these  colonies  exhibit 
characteristic  changes  (Fig.  25).  The  nuclei  become  ranged  in  a 
single  or  double  row  just  beneath  the  capsular  membrane.  Without 
becoming  obviously  differentiated,  these  lumps  of  chromatin  divide 
directly  and  acquire  a  doubly  refractive  character.  Hundreds  of 



minute  crystals  arise  in  the  endoplasm,  a  few  larger  ones  also  in  certain 
Collosphaeridae.  The  single  oil-globule  of  each  capsule  becomes 
very  rapidly  subdivided  into  as  many  minute  vesicles  as  there  are 
nuclei,  and  in  association  with  this  process  a  blue  pigment  develops 


FIG.  23. 

Collosphaera  huxleyi.  Optical  sections  of  different  growth-stages  to  illustrate  (A,  B)  dimor- 
phism (Si,  S'>)  in  early  and  later  stages,  and  (C,  D)  the  formation  of  isospores.  A,  young  actively 
dividing  colony  (the  young  reproductive  phase  of  Brandt,  comparable  with  the. formation  of 
extracapsular  bodies  in  Sphaerozoidae).  Many  individuals  are  naked  central  capsules  with 
one  or  more  nuclei ;  others  have  a  shell  (.S'])  and  are  larger  and  already  provided  with 
zooxanthellae  (z).  B,  later  vegetative  phase.  The  naked  capsules  have  now  secreted  a  large 
shell  (.S2),  and  a  marked  dimorphism  has  resulted.  C,  part  of  a  full-grown  colony  about  to 
sporulate.  The  formation  of  isospores  is  indicated  by  the  grouping  of  the  nuclei.  D,  later 
stage  in  isospore-formation  showing  the  crystals  aggregated  about  the  oil-globule.  x  75. 
(After  Brandt.) 

in  Myxosphaera  coerulea  and  Collosphaera  huxleyi.  Numerous  vacuoles 
arise  in  the  centre  of  the  capsule,  each  with  a  central  granule,  until 
a  number  equivalent  to  that  of  the  nuclei  has  been  formed.  Mean- 
time these  nuclei,  which  have  become  very  numerous,  are  evenly 



disseminated  through  the  endoplasm  forming  the  centres  about  each 
of   which   a    crystal,  an    oil -vesicle,  a   vacuole,   and   granule  are 

Fio.  24. 

Portion  of  a  colony  of  Sphaerozoum  neapolitanum  about  to  form  isospores.  The  spicules  and 
"yellow  cells"  are  omitted.  The  central  capsule  has  disappeared,  and  only  a  thin  peripheral 
ectoplasmic  layer  is  present.  Minute  crystals  are  scattered  through  the  endoplasm,  and  two- 
oil-globules  (o)  are  shown.  X  300.  (After  Brandt.) 

clustered.  The  whole  endoplasm  is  now  transformed  into  a  mass 
of  biflagellated  spores.  The  central  capsule  suddenly  disappears,, 
and  the  ectoplasm,  which  in  the  interval  has  undergone  contraction 



Fio.  25. 

A,  formation  of  isospores  in  Collozoum  inerme.  Two  stages  are  shown  on  opposite  sides  of 
a  central  capsule.  On  the  left  side  the  nuclei  and  crystals  are  aggregated  peripherally,  but  the 
central  oil-globule  is  intact.  On  the  right  the  nuclei  are  smaller  and  more  numerous  and  the 
oil-globule  is  breaking  down.  B,  formation  of  heterospores  in  the  same  shown  by  quadrants, 
a,  early  stage  ;  several  grouped,  modified  nuclei  and  fat-granules  ;  between  the  groups  are  undif- 
ferentiated  nuclei  and  endoplasm ;  6,  c,  and  d  are  later  stages. 

and  degeneration,  breaks  to  pieces.  The  colony  descends  and  the- 
isospores  swarm  out,  leaving  (in  the  Collosphaeridae)  the  large 
crystals  and  the  greater  part  of  the  pigment  behind.  Each  is  a- 



conical  structure  ('012  mm.  long).  From  its  pointed  end  spring 
the  two  cilia,  one  of  which  is  usually  held  in  a  somewhat  horizontal 
position,  the  other  curving  backwards  and  downwards.  Near  this 
end  lies  the  nucleus,  which  has  acquired,  according  to  Brandt 
(10,  p.  163),  a  certain  differentiation.  The  broader  end  is  filled 
with  the  crystal  and  granules  (Fig.  26,  E). 

Heterospwes, — The   formation   of  megaspores   and  microspores 
may  proceed  from  the  same  (Sphaerozoidae)  or  separate  colonies 

FIG.  26. 

Isospores  and  heterospores  of  Radiolaria.  A,  heterospores  of  Xiphacantha  alata  (Acantharia). 
B,  isospores  of  the  same.  C  and  D,  microspore  and  megaspore  of  Collozoum  inerme.  E, 
isospore  of  the  same  showing  crystal  and  inclusions.  F  and  G,  megaspores  of  Sphaerozoum  sp. 
H,  microspores  of  the  same.  (After  Brandt.) 

(Collosphaeridae).  The  process  differs  from  the  development  of 
isospores  in  the  presence  of  segregated  nuclei,  the  differentiation  in 
the  nuclei  of  achromatic  substance,  and  the  dimorphism  of  the  mega- 
and  micro-nuclei.  In  the  Collosphaeridae  the  full-grown  vegetative 
.colony  shows  the  first  traces  of  heterospore- formation  by  the 
segregation  of  its  homogeneous  nuclei  into  groups  of  2,  4,  or  8. 
This  arrangement  is  temporary,  and  very  soon  the  nuclei  are 
found  arranged  in  several  layers,  each  nucleus  being  now  clearly 
composed  of  a  highly  refractive  and  achromatic  ground-sub- 
>stance,  in  which  are  imbedded  thread-like  masses  of  chromatin. 


According  to  the  colony  under  consideration  so  will  these  nuclei 
belong  either  to  the  microspore  or  megaspore.  In  the  former  the 
chromatin  is  disposed  in  stout  granules  and  thick  strands,  in  the 
latter  in  much  smaller  quantity.  In  other  respects  the  colony 
behaves  precisely  as  in  the  formation  of  isospores. 

In  the  Sphaerozoidae  the  formation  of  heterospores  takes  place 
both  in  small,  apparently  young,  colonies  that  bear  extracapsular 
bodies  and  also  from  full-grown  vegetative  colonies.  In  both  cases 
many  of  the  nuclei  become  segregated  and  differentiated,  the  endo- 
plasm  in  which  they  lie  acquires  distinctive  characters,  and  the 
groups  so  formed  are  separated  by  undifferentiated  plasma  and 
nuclei  (Fig.  25,  B).  The  oil-globule  becomes  subdivided  into  a  grape- 
like  mass,  which  ultimately  splits  up  into  minute  granules,  and 
these  are  collected  around  the  specialised  nuclei.  In  the  case  of 
colonies  bearing  extracapsular  bodies  the  whole  of  this  bud  becomes 
transformed  into  megaspores,  the  contents  of  the  central  capsule 
becoming  microspores.  In  older  colonies  the  endoplasm  is  con- 
verted into  a  vast  number  of  portions,  in  each  of  which  the  differ- 
entiated nuclei  are  aggregated.  These  nuclei  are,  however,  not  all 
of  one  kind.  Each  collection  is  either  meganucleate  or  micro- 
nucleate,  and  accordingly  stains  feebly  or  strongly.  The  contents 
of  the  capsule  now  becomes  resolved  into  biflagellated  megaspores 
and  microspores,  the  ectoplasm  degenerates  and  collapses,  the 
central  capsule  deliquesces,  and  the  spores  become  disseminated. 

Little  is  as  yet  known  as  to  the  formation  of  isospores  and 
heterospores  in  other  Radiolaria.  In  Acanthochiasma  rubescens 
(Acantharia)  Brandt  records  the  early  development  of  two  kinds  of 
bodies — one  with  crystalloid  inclusions,  the  other  with  lobulated 
masses  of  fat.  The  same  observer  has  described  the  active  spores 
of  XipJiacantha  alata  and  Acanthometra  sicula.  Two  kinds  of  spores 
occur  in  these  Acantharia  (Fig.  26,  A,  B).  Both  are  minute 
('004  mm.  long),  and  provided  with  three  cilia,  which  spring  from 
the  two  poles  of  the  spheroidal  or  pear-shaped  body,  but  they  differ 
in  that  the  spores  of  any  one  individual  either  contain  a  minute 
crystal  and  few  granules  or  many  granules  but  no  crystal.  Both 
are  provided  with  a  starch-grain  (see  pp.  128),  and  traces  of  the 
yellow  cells  of  the  parent  occur  in  the  granular  variety.  It  seems 
highly  probable,  therefore,  that  crystal-bearing  isospores  and  granular 
heterospores  occur  in  this  sub-class  as  in  the  Spumellaria ;  but 
although  the  results  of  more  recent  expeditions  have  extended  very 
largely  the  number  of  Acantharia  in  which  the  early  development 
of  spores  has  been  shown  to  occur,  the  free  spores  have  not  been 
again  noticed;  nor  do  we  possess  any  exact  observations  on  the 
flagellated  bodies  that  have  occasionally  been  seen  in  Nassellaria 
and  Phaeodaria. 




SUB-CLASS  I.     PERIPYLARIA  (Spumellaria). 

Central  capsule  homaxonic,  uniformly  perforated  by  numerous  similar 
and  extremely  small  pores.  Skeleton  siliceous.  Extra-capsulum  volum- 
inous (except  in  Physematiidae). 

ORDER  1.  Collodaria. 

Large  monozoic  forms  not  forming  a  true  coenobium.  Skeleton  absent 
or  spicular. 

FAMILY  1.  PHYSEMATIIDAE.  Large  vacuoles  confined  to  the  endoplasm. 
No  stratified  concretions  in  the  latter.  No  pigment.  Few  "  yellow  cells." 
Nucleus  spherical,  with  smooth  membrane  and  a  few  rounded  nucleoli. 
Selected  forms : — Physematium  miilleri,  H.  ;  Thalassolampe  margarodes,  H., 
Mediterranean  and  Canary  Islands  ;  Lampoxanthium  murrayanum,  Fowl., 
Faroe  Channel.  The  genus  Actissa  of  Haeckel  is  an  early  stage  of  growth 
of  some  species  of  this  family. 

FAMILY  2.  THALASSOPHYSIDAE.  Large  vacuoles  extracapsular. 
Structure  similar  to  that  of  the  Thalassicollidae,  but  nuclear  membrane 
usually  tubercular  or  papillary.  Reproduction  by  rapid  and  peculiar 
fragmentation  (Fig.  21).  Spores  unknown.  Selected  forms  : — Thalas- 
siosolen  atlanticus,Wolf.  (28);  Thalassophysa  pelagica,  H.  (Fig.  1),  Faroe 
Channel ;  T.  sanguinolenta,  H.  ;  T.  papillosa,  H.,  Mediterranean  and 
Canary  Islands  (often  deformed  by  ingested  Coccolithophoridae).  For 
further  account  of  this  family  see  Brandt  (25). 

FAMILY  3.  THALASSICOLLIDAE.  Nuclear  membrame  smooth  and 
spherical.  Stratified  concretions  present  in  the  endoplasm.  Multiplica- 
tion by  binary  fission,  by  isospores,  and  by  heterospores  (see  Fig.  2  ; 
Brandt  [25,  25a,  and  26]).  Selected  forms  : — Thalassicolla  nucleate/,,  Hux., 
Valencia  Harbour,  Faroe  Channel,  and  cosmopolitan  ;  T.  spumida,  H., 
Canary  Islands ;  T.  pellucida,  H.,  cosmopolitan. 

FAMILY  4.  THALASSOTHAMNIDAE,  Hacker  (37).  Skeleton  in  the 
form  of  a  large  single  radiate  spiculum  or  of  a  double  spiculum.  Central 
capsule  sometimes  spherical,  characteristically  lobed  or  branched. 
Nucleus  complex.  Nuclear  membrane  crenate  (Fig.  14).  Endoplasm  with 
stratified  inclusions.  Selected  forms  : — Thalassothamnus  ramosus,  Hack., 
Antarctic  ;  Cytocladiis  spinosus,  Schroder  (Fig.  10),  Japan  Seas  (38). 

FAMILY  5.  OROSPHAERIDAE.  Protoplasm  organised  as  in  the  preceding 
family.  Skeleton  a  perforated  shell  with  branched  and  thorny  spines. 
Orosphaera,  H.,  deep  water  of  mid-Atlantic.  This  family  has  been  re- 
moved by  Hacker  (37)  from  the  Phaeodaria,  with  which  group  Haeckel 
associated  it ;  but  if  the  presence  of  a  phaeodium,  astropyle,  and  parapyles 
is  confirmed,  its  systematic  position  will  have  to  be  revised. 

1  The  number  of  genera  and  species  in  this  class  is  so  large  that  only  a  selection 
can  be  referred  to  here.  North  Atlantic  forms  have  been  chiefly  selected. 


ORDER  2.  Sphaerozoa. 

Colonial  forms. 

FAMILY  1.  SPHAEROZOIDAE.  Both  mega-  and  microspores  developed 
in  the  same  individual.  A  lattice-shell  absent.  Selected  forms:  — 
Collozoum  inerme,  Norway  (Figs.  3,  s,  and  25)  ;  C.  pelagicum,  Shetlands  ; 
Sphaerozoum  ovodimare,  Faroe  Channel. 

FAMILY  2.  COLLOSPHAERIDAE.  Mega-  and  microspores  in  separate 
individuals.  Skeleton,  when  present,  takes  the  form  of  a  lattice-shell 
with  or  without  associated  spicules.  Selected  forms  : — Oollosphaera  huxleyi, 
Mediterranean  (Fig.  23)  ;  Choenicosphaera  murrayana,  Shetlands. 

This  order  is  treated  fully  by  Brandt  in  his  Monograph  (10)  and  (22). 

ORDER  3.  Sphaerellaria. 

SUB-ORDER  1.  SPHAEROIDEA.  Central  capsule  and  shell  (or  shells) 
spherical.  Selected  forms  : — Hexalonche  philosophica,  H.,  Faroe  Channel ; 
Hexacontium  enthacanthium,  Jorg.  ;  H.  pachydermum,  Jorg.,  North  Sea  ; 
Hexadoras  borealis,  Clev.,  North  Sea ;  Echinomma,  leptodermum,  Jorg., 
Norway  and  Sweden  ;  Rhizoplegma  boreale,  Clev.,  Norway. 

SUB-ORDER  2.  PRUNOIDEA.  Central  capsule  and  shell  elliptical  or 
cylindrical ;  often  with  transverse  constrictions.  Selected  form  : — Pruno- 
carpus  datura,  H.,  Faroe  Channel. 

SUB-ORDER  3.  DISCOIDEA.  Central  capsule  and  shell  discoid  or 
lenticular;  often  much  flattened.  Selected  forms:  —  Trochodiscus 
heliodes,  Cler.,  North  Sea  ;  T.  echiniscus,  H. ;  Lethodiscus  microporus,  H. ; 
Astrosestrum  acanthastrum,  H.  ;  Spongodiscus  favus,  Ehr.,  Faroe  Channel. 

SUB-ORDER  4.  LARCOIDEA.  With  lentelliptical  central  capsule  and 
shell.  Selected  forms  : — Lithelius  minor,  North  Sea  ;  L.  arborescens,  H., 
Faroe  Channel  ;  Phorticium  pylonium,  H.,  Norway  and  Sweden. 

SUB-ORDER  5.  SPHAEROPYLIDKA.  With  basal  or  basal  and  apical 
pylome  (large  opening  to  the  shell).  See  Dreyer  (15). 


Radiolaria  in  which  the  skeleton  is  composed  neither  of  the  so-called 
horny  acanthin  nor  of  silica,  but  (in  many  cases)  of  strontium  sulphate. 
The  central  capsule  is  perforated  uniformly  or  in  networks  and  segregated 
pores.  The  skeleton  has  the  form  of  spicules  radiating  from  a  central 
point  within  the  capsule  (Acanthometrida).  Rarely  a  fenestrated 
extracapsular  skeleton  is  added  (Acanthophractida). 

ORDER  1.  Acanthometrida. 

SUB-ORDER  1.  ACTINELIIDA.  With  10-200  radial  or  diametral  spines 
not  arranged  according  to  Miiller's  Law  (p.  132). 

FAMILY  1.  ASTROLOPHIDAE.  Spines  radiating  from  a  common  centre. 
Genus  1.  Adinelius.  All  spines  of  equal  length  and  similar  shape.  A. 
purpureus,  H.,  Mediterranean.  Genus  2.  Astrolophus.  Spines  of  unequal 



It  is  probable  that  further  investigation  of  the  Actineliida  will  clear 
up  the  anomalies  that  at  present  attach  to  their  isolated  position.  They 
are  regarded  by  Haeckel  as  the  ancestral  stock  of  the  whole  Itadiolaria. 
The  family  Litholophidae  which  he  associated  with  them  is  now  regarded 
as  composed  of  growth-stages  of  the  genus  A  canthonia. 

FAMILY  2.  ACANTHOCHIASMIDAE.  "With  ten  or  sixteen  diametral 
spines  irregularly  arranged.  Genus  Acanthochiasma.  With  ten  spines, 
A.  fusiforme,  found  near  Plymouth  and  in  the  North  Sea.  A.  cruciata, 
A.  krohnii,  generally  distributed  in  the  Atlantic. 

SUB-ORDER  2.  ACAXTHOXIIDA.  With  twenty  spines  arranged  in  four 
zones  of  five  spines  to  each  (Muller's  Law). 

FAMILY  1.  ACANTHOMETRIDAE.  Spicules  circular  in  transverse 
section.  Genera — Acanthometron  ;  proximal  end  of  spines  without  flange  ; 
A.  pellucidum,  N.  and  E.  Scotland.  Phyllostaurus,  with  flange ;  Ph. 
quadrifolius,  abundant  in  North  Atlantic. 

FAMILY  2.  ZYGACANTHIDAE.  Spines  compressed  and  double-edged, 
lanceolate  in  section.  Genus — Zygacantha,  without  flange  at  base  of 
spines  ;  Z.  septentrionalis,  North  Atlantic. 

FAMILY  3.  ACANTHONIIDAE.  Spines  cruciform  in  cross  section. 
Genus  —  Acanthonia ;  A.  rnulleri,  N.  Scotland  and  North  Sea;  A. 
ligurina,  W.  coast  of  Greenland  ;  Acanthonidium ;  A.  echinoides,  North 
Sea,  Faroes  and  Norway ;  A.  pallidum,  N.  and  E.  coasts  of  Scotland. 

FAMILY  4.  AMPHILONCHIDAE.  Two  opposite  spines  much  larger  than 
the  rest.  Genus — Amphilonche.  A.  belonoides,  generally  distributed 
in  the  Atlantic.  For  the  exotic  family  Lithopteridae,  see  Haeckel's 
Monograph  (11). 

ORDER  2.  Acanthophractida. 

SOB-ORDER  1.  SPHAEROPHRACTA.  With  twenty  radial  spines  of 
equal  size.  Shell  spherical. 

FAMILY  1.  SPHAEROCAPSIDAE.  Shell  composed  of  very  numerous 
small  plates  each  with  a  single  pore.  Genera — 1.  Sphaerocapsa.  Sph. 
cruciata,  Faroes,  North  Atlantic.  2.  Astrocapsa.  A.  tritonis  and  A. 
coronata,  Faroes  and  North  Atlantic.  3.  Porocapsa.  P.  murrayana.  4. 
Cannocapsa.  G.  osculata,  Faroe  Channel  and  North  Atlantic. 

FAMILY  2.  DORATASPIDAE.  Shell  composed  of  the  meeting  branches 
of  two  to  four  apophyses  given  off  by  the  twenty  radial  spines.  Seventeen 
genera  are  known,  mostly  from  equatorial  or  southern  waters. 

FAMILY  3.  PHRACTOPELTIDAE.  Shell  double ;  the  inner  one 
enclosed  by  the  central  capsule.  No  genera  known  from  northern 

SUB-ORDER  2.  PRUNOPHRACTA.  Two  or  six  spines  much  larger  than 
the  rest.  Shell  not  spherical. 

FAMILY  1.  BELONASPIDAE.  Shell  ellipsoidal.  Two  enlarged  spines. 
The  genus  Platnaspis  occurs  in  North  Atlantic  and  Mediterranean. 

FAMILY  2.  HEXALASPIDAE.  Shell  lentelliptical.  Six  enlarged 
spines.  The  genus  Hexaconus  is  known  from  the  North  Atlantic. 

FAMILY  3.  DIPLOCONIDAE.  Shell  diploconical  with  two  opposite 
large  funnels  (the  sheaths  of  the  two  enlarged  spines).  Pseudopodia  con- 


fined  to  the  two  polar  apertures.     The  genus  Diploconus  is  known  from 
the  Mediterranean. 

SUB-CLASS  III.     MONOPYLARIA  (Nassellaria). 

Radiolaria  with  monaxonic  central  capsule  that  bears  at  one  pole  a 
porous  plate  forming  the  base  of  an  inwardly  directed  cone. 

SOB-LEGION  1.  Plectellaria. 

Without  a  complete  lattice-shell. 

ORDER  1.  PLECTOIDEA.  Skeleton  a  basal  tripod  (Fig.  5).  Selected 
forms  : — Plagiacantha  arachnoides,  Clap.,  W.  coast  of  Norway,  North  Sea  ; 
Plagiocarpa  procyrtella,  EL,  North  Atlantic,  Iceland  ;  Hexaplagia  arctica, 
H.,  Greenland  ;  Polyplagia  novenaria,  H.,  Faroe  Channel,  North  Atlantic  ; 
Plectophora  arachnoides,  H.,  and  PI.  novena,  H.,  North  Atlantic  and  Faroe 
Channel,  North  Sea. 

ORDER  2.  STEPHOIDEA.  Skeleton  a  sagittal  ring,  and  usually  no 
tripod.  Selected  forms  : — Lithocircus  annularis,  Mull.  ;  Cortiniscus 
iypicus,  H.  ;  Eucoronis  nephrospyris,  H.  ;  all  cosmopolitan. 

SUB-LEGION  2.  Cyrtellaria. 

Skeleton  a  complete  lattice-shell  (cephalis). 

ORDER  1.  SPYROIDEA.  Cephalis  bilocular  with  cephalic  construction. 
Almost  exclusively  southern  forms. 

ORDER  2.  BOTRYOIDEA.  Cephalis  multilocular.  Selected  forms  : — 
Sotryocampe  inflata,  Ehr.,  cosmopolitan  ;  Phormobotrys  hexaihalomia,  H., 

ORDER  3.  CYRTOIDEA.  Cephalis  single,  without  constrictions  or  lobes. 
Selected  forms : — Tridictyopus  elegans,  Hert.,  Mediterranean  ;  Cornutella 
£lathrata,  Ehr.,  cosmopolitan  ;  Cyrtocalpis  obliqvM,  H.,  cosmopolitan  ; 
Lithomelissa  thoracites,  H.,  cosmopolitan  ;  L.  setosa,  H.,  Norway  ;  Eucecry- 
phalus  gegenbauri,  H.,  cosmopolitan  ;  Carpocanium  diadema,  H.,  cosmo- 
politan ;  Dictyocephalus  ocellatus,  H.,  Faroe  Channel  ;  Dictyophimus  clevei, 
Jorg.,  Norway ;  Theoconus  ariadnes,  H.,  cosmopolitan  ;  Cladoscenium 
tricolpium,  Norway  ;  Clathrocyclas  craspedota,  Norway. 

SUB-CLASS  IV.     TRIPYLARIA  (Phaeodaria). 

Radiolaria  in  which  the  central  capsule  is  double  and  usually 
possesses  a  chief  aperture  (astropyle)  and  two  accessory  apertures  (para- 
pyles).  A  dense  resistant  pigment  (phaeodium),  probably  of  excretory 
nature,  accumulates  in  the  extracapsulum.  The  skeleton  is  siliceous  and 
.often  made  up  of  hollow  tubes. 

ORDER  1.  Phaeocystina. 

The  skeleton  consists  of  isolated  spicules. 

FAMILY  1.  AULACANTHIDAE.  Skeleton  of  tangential  needles  and  radial 
;hollow  rods.  Selected  forms : — Aulacantha  scolymantha,  H.,  Hebrides, 



Faroe  Channel,  Shetlands  ;  Aulographis  zetesios,  Borg.  ;  A.  furcellata, 
Wolf.,  Faroe  Channel ;  Au.  tetrancistra,  H.,  Norway  ;  Aulodendron  boreale, 
Wolf.,  Faroe  Channel. 

ORDER  2.  Phaeosphaeria. 

Skeleton  composed  of  an  extracapsular  shell  or  of  two  concentric 
shells  separated  by  the  extracapsulum.  Outer  shell  usually  spherical. 

FAMILY  1.  SAGOSPHAERIDAE.  Outer  shell  a  lattice-work  with 
triangular  or  areolar  meshes.  Selected  forms  : — Sagena  ternaria,  H.  ; 
Sagosphaera  trigonilla,  H.,  cosmopolitan  ;  Sayenoarium  sp.,  Jorg,  Norway. 

FAMILY  2.  AULOSPHAERIDAE.  An  outer  lattice-shell  alone  present, 
the  hollow  bars  of  which  contain  septa.  Selected  forms : — Aulosphaera 
flexuosa,  H.,  Faroe  Channel ;  Auloscena  verticillatus,  H., Norway ;  Aulotractus 
fusulus,  H.,  Faroe  Channel,  Hebrides. 

FAMILY  3.  CANNOSPHAERIDAE.  Inner  and  outer  lattice- shells  present, 
interconnected  by  radii.  Cannosphaera  antarctica,  H.,  bipolar  form. 

FAMILY  4.   POROSPATHIDAE.     Inner  shell  alone  present,  composed  of 

two  finely  grained  membranes  ;  elliptical 

*EXO.  or  ovoid.     Mouth  at  the  end  of  a  curved 



ORDER  3.  Phaeogromia. 



A  single  simple  shell  present,  variable 
in  shape,  but  always  provided  with  a 
projecting  peristome. 

monaxonic,  composed  of  two  layers  which 
exhibit  an  extremely  fine  diatomaceous 
graining.  Peristome  toothed.  Selected 
forms  : — Lithogromia  silicea,  H.,  Faroe 
Channel ;  Protocystis  tritonis,  H.,  Faroe 
Channel,  Shetlands,  North  Sea ;  Pr, 
tridens,  H.,  Norway  and  Sweden  ;  Pr. 
harstoni,  Murray,  Norway  ;  Pr.  xiphodon, 
H.,  Faroe  Channel ;  Challevgeron  trioden, 
balfouri,  golfense,  johannis,  armatum  (Fig. 
27) ;  Cadium  melo,  Clev.  ;  Pharyngella 
gastrula,  H.  ;  Entocannula  hirsuta,  H.  ; 
Faroe  Channel. 

shell  alveolar.  Peristome  with  articulated 

surroundedby  processes  and  its  aborai   feet     ^  secondary  shell  may  be  developed 
surface  bears  a  crest  (Exo).    The  central    .  .  *  J 

capsule  possesses  two  astropyles  (As),   in  relation  to  the  phaeodium. 

two  parapyles,   and  two   nuclei.     The  A      q       11    t  (avertm-ncr   0-1     mm 

brown  phaeodellae    (Ph)    are    shown.  *•    »lndil  S  ^averaging  U  1    mm, 

(From  a  living  specimen,  after  Borgert.)  in  diaui.),  with  primary  shell  and    few 

radial    spines.      Phaeodium    in    primary 

shell.       Euphysetta    nathorsti,    Clev.,    North    Sea,    Scotland  ;    Mediisetta 
tiara,  H.,  Faroe  Channel. 

B.  Small  forms  (0-8--3  mm.),   with  hooded  primary  shell  provided 

Fia.  27. 

Challengeron  armatum,  Borg.     x  225 
The  mouth  (M)  of  the  perforated  shell  is 



with   six    long    radial    spines.     Phaeodium   still   in   the    primary    shell. 
Gazelletta,  Fowler. 

C.  Large    forms,    with    conical    shell,    completely    filled    by    central 

FIG.  28. 

Atlanllcella  craspedota, 
Borgert.  In  this  newly 
discovered  family  of  Phaeo- 
daria  the  central  capsule 
(C.c)  is  a  large  inflated 
4  -  lobate  structure.  The 
skeleton  consists  of  a  me- 
dian hollow  part  (M.Sk)  and 
of  four  pendent  septate 
arms  (Sp).  The  black  area 
is  the  phaeodium  (Ph). 
x  50.  (After  Borgert.) 


capsule,  which  is  converted  into  a  swim-bladder.  A  diaphragm,  perfor- 
ated (Hacker  [37])  by  several  astropyles  and  parapyles,  separates 
endoplasm  from  ectoplasm  (Fig.  12).  Phaeodium  outside  primary 


FIG.  29. 

Planktonetta  atlantica,  Borgert. 
(After  Fowler.)  x  66.  The  entire 
animal  is  shown  as  seen  in  a  pre- 
served specimen.  One  pair  of  arms 
is  omitted.  The  central  capsule 
(End)  is  invested  by  a  skeletal 
membrane  and  forms  a  float.  The 
arms  are  embedded  in  the  phaeo- 
dium (Ph)  and  attached  to  this 
is  the  outer  shell  (F),  comparable 
with  that  of  Medusetta  and  Atlanti- 
cella.  A  section  through  this 
animal  is  seen  at  Fig.  12,  p.  120. 


shell,    with    intra-phaeodial   skeleton.      A    float   present.      Planktonetta 
atlantica,  Borg.,  Faroe  Channel  (29,  37). 

D.  Large  forms,  without  primary  shell.  Central  capsule  a  swim- 
bladder.  Diaphragm  and  phaeodial  skeleton  as  in  preceding  sub-family. 
Secondary  shell  projecting  over  peristome.  No  float.  Nationaletta. 


E.  Mid-sized  forms,  without  primary  shell.  Secondary  shell  with 
four  arms.  Atlanticella.  (Fig.  28.)  Borgert  (21). 

FAMILY  3.  CASTANELLIDAE.  Primary  shell  two -layered  and  com- 
posed of  (1)  extremely  delicate  tangential  siliceous  needles;  (2)  the 
two  conjoined  limiting  membranes  of  the  two  layers,  united  by  (3)  a 
porcellanous  impregnation.  Selected  form  :  —  Castanidium  apsteini, 
bipolar  (36). 

FAMILY  4.  CIRCOPORIDAE.  Shell  composed  as  in  Family  3,  but 
spherical,  polyhedral,  or  multipolar  (36). 

FAMILY  5.  TOSCARORIDAE  (Fig.  30).  Shell  rarely  spherical,  gener- 
ally monaxonic.  Nucleus  elongated  with  sigmoid  chromatin  band. 
(Borgert  [2 la].) 

FIG.  30. 

Tuscaroridae.  A,  Tuscarusa  globosa,  Borgert,  showing  the  peristomial  hollow  spines ; 
the  rest  are  broken  off.  x  39.  B,  Tuscarora  nationalis,  Borgert,  showing  the  two  central 
capsules  in  the  shell.  Each  capsule  contains  a  bent  nucleus,  x  24.  (After  Borgert.) 

ORDER  4.  Phaeoconchia,  H. 

Central  portion  of  the  skeleton  in  the  form  of  two  valves,  free  or 
hinged  together. 

FAMILY  1.  CONCHARIDAE,  H.  With  thick  valves,  which  are  devoid 
of  an  apical  cupola  and  of  radial  tubes.  Equatorial  and  southern 

FAMILY  2.  COELODENDRIDAE.  "With  extremely  thin  valves,  each  of 
which  bears  a  cupola  and  tubular  processes.  Goelodendron  ramosissimum, 
Faroe  Channel  and  cosmopolitan. 

FAMILY  3.  COELOGRAPHIDAE.  Each  cupola  provided  with  a  hollow 
process  (rhizocanna),  which  communicates  with  the  cupola  by  a  paired 
or  unpaired  frenulum.  Radial  tubes  strongly  developed,  sometimes 
forming  an  outer  bivalved  mantle.  The  largest  and  most  complex 


Fio.  31. 

Coelothamnus  davidoffii,  Btitschli ;  one  of  the  Phaeodaria.  Entire  animal  drawn  from  a  dead 
specimen,  x  4.  Sixteen  radii  spring  from  the  bivalve  shell  (S)  which  encloses  the  central 
capsule.  The  ectoplasm  (E)  is  shown  investing  the  skeleton  which  supports  it  on  the  anchor- 
like  extremities  of  its  tufted  appendages.  (After  Btitschli.) 

Radiolaria    (20-30     mm.    in    diara.).       Selected    forms: — Coeloplegma 
murrayanum,  H.  (Fig.  32)  ;  G.  tritonis,  H.,  Faroe  Channel. 


Fio.  32. 

Central  capsule  and  adjacent  structures  of  Codoplegma  murrayanitm,  H.;  one  of  the  Coelo- 
graphidae.  The  bivalve  shell  (S)  supports  the  hollow-branched  galea  (G),  in  which  the  phaeo- 
dellae  are  seen  emerging  through  the  aperture  (R)  of  the  nasal  tube  (rhizocanna).  The  astropyle 
(As)  is  drawn  out  into  a  tube. 


1.  Ehrenberg,  Ch.  G.     Monatsberichte  d.  Berliner  Akad.  1844-73. 

2.  -     -    (Fossil  Species.)     Abhandl.  d.  k.  Akad.  Berlin,  1872,  pp.  131-397. 

3.  Huxley,   T.  H.     (Thalassicolla.)    Annals  and  Mag.  Nat.  Hist.  vol.  viii., 

1851,  pp.  433-442. 


4.  Miiller,.  J.     (Fundamental  Treatise.)      Abhaudl.   d.   Berliner  Akad.  1858, 

pp.  1-62. 

5.  Haeckel,  E.  Die  Radiolarien.     Berlin,  1862. 

6.  Cienkowski.  (Yellow  Cells.)    Archiv  f.  mikros.  Anat.  vii.,  1871,  pp.  372-381. 

7.  Hertwig,  R.  (Structure  of  Radiolaria. )     Jenaische  Denkschriften,  vol.  ii., 

1879,  pp.  129-277. 

8.  Biitschli,  0.     (Skeleton  of  Nassellaria.)     Zeit.   f.  wiss.  Zool.  vol.  xxxvi., 

1881,  pp.  485-540. 

9.  (Monograph.)    Bronn's  Thierreich,  Protozoa,  vol.  i.,  1885,  pp.  332-478. 

10.  Brandt,  K.     (Sphaerozoa.)     Fauna  v.  Flora  d.  Golfes  von  Neapel,  vol.  xiii., 

10a.  (Zooxanthellae.)     Mittheil.  Stat.  Neapel,  iv.,  1883. 

11.  Haeckel,  E.     (Monograph.)     Challenger  Reports,  vol.  xviii.,  1887. 

12.  Lankester,    E.    Ray.       Radiolaria    in    Encyclopaedia    Britannica,    Art. 

"Protozoa,"  pp.  20-23  of  reprint. 

13.  Famintzin,    A.      (Life -History,  Food,  and  Yellow  Cells  of  Sphaerozoa.) 

Memoires  de  1'Acad.  Sci.  St.  Petersbourg,  7th  series,  vol.  xxxvi.  No.  16, 
1889,  p.  21. 

14.  Verworn.     (Thalassicolla.)     Pfliiger's  Archiv  f.  Physiologic,  vol.  li.,  1891, 

p.  118. 
14a.  (Hydrostatics.)     Ibid.  vol.  liii.,  1893,  pp.  140-155. 

15.  Dreyer,    F.      (Evolution   of  Radiolarian    Skeleton.)      Jenaische    Zeit.  f. 

Naturwiss.  vol.  xxvi.,  1892,  pp.  204-468. 

16.  Karawiew.      (Fission  in  Aulacantha.)     Mem.  Soc.  Natur.  Kiew.  vol.  xv., 


17.  Borgert,  A.     (Reproduction  of  Tripylaria.)     Annals  and  Mag.  Nat.  Hist. 

(6),  xviii.,  1896,  pp.  422-426. 

18.  (Fission  in  Aulacantha.)     Spengel's  Zool.  Jahrb.  Anat.   vol.  xiv., 

1900,  pp.  203-274. 

19.  (North  Atlantic  Tripylaria.)     Nordisches  Plankton,  Lief,  i.,  1901, 

pp.  1-52. 

20.   (Tripylaria  of  the  German  Plankton  Expedition. )     Zool.  Jahr.  Syst. 

vol.  xix.,  1904,  pp.  733-760. 

21.  (Atlanticellida.)     Ergeb.  Plankton-Expedition,  vol.  iii.,  1906. 

21a. (Tuscaroridae. )     Ibid.  vol.  iii.,  1906. 

22.  Vernon,    H.   M.      (Respiration  in   Collozoum.)      Journal    of  Physiology, 

vol.  xxi.,  1897,  p.  443. 

23.  Brandt,  K.    (Bionomics  of  Acantharia.)    Ergebnisse  d.  deutschen  Plankton- 

Expedition,  vol.  i.,  1892,  p.  338. 

24.  (Hydrostatics.)     Zool.  Jahrbiicher  Syst.  vol.  ix.,  1895,  pp.  27-74. 

25.  (Thalassophysidae.)     Archiv  f.  Protistenkunde,  vol.  i.,  1902. 

25a.  (Division  of  Thalassicolla.)     Mitteil.  d.  Vereins  Schlesw.-Holstein. 

Aerzte,  12.  Heft,  1890. 

26.  (Thalassicollidae.)     Ibid.  vol.  vi.,  1905,  pp.  245-271. 

27.  (Classification  of  Sphaerozoa.)     Zool.  Jahrb.  Suppl.  vol.  viii.,  1905, 

pp.  311-352. 

28.  Wolfendcn,  R.  N.     (Radiolaria  of  Faroe  Channel  and  Shetlands.)     Journal 

Marine  Biol.  Assoc.  N.S.  vol.  vi.,  1902,  No.  3.     Trans.  Linn.  Soc.  vol.  x., 
pt.  4,  1905. 

29.  Fowler,  G.  H.     (Planktonetta.)     Quart.  Journ.  Mic.  Sci.  (2),  vol.  xlvii., 

1903,  pp.  133-143. 


30.  Fowler,  G.  H.     (GazellcUa.)    Quart.  Journ.  Mic.  Sci.  (2),  vol.  xlviii.,  1904, 

pp.  483-488. 

31.  -     -    (Radiolaria  of  Faroe  Channel.)   Proc.  Zool.  Soc.  1896-98,  pp.  991,  523, 


31a.  Popowsky,  A.     (North  Atlantic  Acantharia.)     Nordisches  Plankton,  Lief, 
iii.,  1905,  pp.  43-69  ;  Lief,  v.,  1906. 

32.  (Acantharia.)     Ergeb.   Plankton -Expedition,   1904;   Appendix  in 

Archiv  f.  Protistenkimde,  vol.  v.,  1905,  pp.  339-357. 

33.  Schcwiakoff,    W.      (Skeleton,    Myonemes,    and   Flotation   of  Acantharia.) 

Me'moires  de  1'Acad.  des  Sci.  St.  Petersbourg,  vol.  xii.,  1902,  No.  10. 

34.  Immermann,  F.     (Aulacanthidae.)     Ergeb.  Plankton-Expedition,  vol.  iii., 


35.  Hacker,  V.     (Biological  Significance  of  Tripylarian  Skeleton.)     Jenaische 

Zeitschrift  f.  Naturwiss.  vol.  xxxix.,  1905,  pp.  581-648  ;  Zeit.  f.  wiss. 
Zool.  vol.  Ixxxiii.,  1905,  pp.  336-375  ;  Archiv  f.  Protistenkunde,  vol.  ix., 
1907,  pp.  139-169. 

36.  (Challengeridae,  Tuscaroridae,  Circoporidae  of  the  Valdivia  Expedi- 
tion.)   Archiv  f.  Protistenkunde,  vol.  viii.,  1906  ;  and  Verhandl.  deutsch. 
zool.  Gesellschaft,  vol.  xiv.,  1906,  pp.  122-156. 

37.  (Thalassothamnidae,  Medusettidae. )    Zool.  Anzeiger,  vol.  xxx. ,  1906, 

No.  26,  pp.  878-895  (16  figs.). 

38.  Schroder,  0.     (Cytocladus.)     Zool.  Anzeiger,  vol.  xxx.,  1906,  pp.  448  and 


39.  ButscJili,  G.     (Strontium  Sulphate  in  Skeleton  of  Acantharia,  etc.)     Zool. 

Anzeiger,  vol.  xxx.,  1906,  No.  24,  pp.  784-789. 

40.  Delap,  M.  and  C.     (Irish  Thalassicollidae.)     Scientific  Investigations,  Irish 

Fisheries,  1905  (vii.)  [1906]. 

41.  Keeble,  F.,  and  Gamble,  F.  W.     (Green  Cells  of  Convoluta. )     Quart.  Journ. 

Micr.  Sci.  vol.  1L,  1907,  pp.  167-219. 

42.  Schaudinn,  F.     (Trichosphaerium.)     Abhandl.  d.  kgl.  preuss.  Akad.  Wiss. 

Berlin,  Supplement,  1899. 

43.  Patter,  E.      (Respiration  of  Protozoa.)      Zeit.  f.  allgemeine  Physiologic, 

vol.  v.,  1905,  pp.  566*612.     Ibid.  vol.  vii.  pp.  46-53. 

44.  Hinde,  J.   G.     (Fossil  Radiolaria.)     Quart.  Journ.  Geol.  Soc.  vol.  Iv.  pp. 


45.  Johnstone,  J.      (Summary  of  Recent  Work  on  Marine  Nitrogenous  Food- 

Stuffs.)     Science  Progress  (N.S.),  vol.  ii.,  1907,  pp.  191-210. 

46.  Klebs,  G.     (Yellow  Cells  and  Peridinians.)     Bot.  Zeitung,  vol.  xlii.,  1884, 

p.  721. 

THE  PEOTOZOA  (continued) 



Order  1.  Monadidea. 

Tribe  1.  Pantostomatina. 
Sub-Tribe  1.  Holomastigoda. 
^  „         2.  Rhizomastigoda. 
Tribe  2.  Protomastigina. 

Sub-Tribe  1.  Monomastigoda. 
„          2.  Paramastigoda. 
„          3.  Heteromastigoda. 
„         4.  Isomastigoda. 
Tribe  3.  Polymastigina. 
Sub-Tribe  1.  Trimastigina. 
,,         2.  Monostomatina. 
„         3.  Distomatina. 
„         4.  Lophomonadina. 
Order  2.  Euglenoidea. 
Tribe  1.  Euglenina. 
„     2.  Astasiina. 
„     3.  Peranemina. 
Order  3.  Chromomonadidea. 
Tribe  1.  Chloromonadina. 
„     2.  Chrysomonadina. 
,,     3.  Cryptomonadina. 
Order  1.  Craspedomonadina. 

„      2.  Phalansteriina. 
Order  1.  Chlamydomonadina. 

„      2.  Volvocina. 


Tribe  1.  Gymnodiniaceae. 

,,     2.  Prorocentraceae. 

„     3.  Peridiniaceae. 



1  By  Arthur  Willey,  F.R.S.,  and  Prof.  S.  J.  Hickson,  F.R.S. 


THE  unicellular  organisms  which  are  associated  in  the  class  Mastigo- 
phora  or  Flagellata  in  the  wide  sense,  comprise  a  very  heterogeneous 
assemblage  of  forms,  having  in  common  the  possession  of  certain 
characteristic  traits  of  organisation  (a  single  nucleus,  one  or  more 
contractile  vacuoles,  one  or  more  flagella),  and  further  united  together 
phyletically  by  the  occurrence  of  transitional  or  annectant  types. 

Our  knowledge  of  the  group  dates  back  to  the  time  of  Anton 
Leeuwenhoek,  at  the  beginning  of  the  eighteenth  century,  while 
the  foundation  of  the  modern  system  may  be  safely  attributed  to 
the  labours  of  Christian  Gottfried  Ehrenberg  during  the  early  part 
of  last  century  (1830-1838). 

From  the  most  general  point  of  view  the  peculiar  biological 
interest  of  the  Mastigophora  rests  upon  the  fact  that,  in  this  more 
than  in  any  other  class  of  Protista,  the  formal  distinctions  which 
are  commonly  drawn  between  the  animal  and  vegetable  kingdoms 
vanish.  It  was  formerly  a  question  whether  such  and  such  an 
order  of  Mastigophora  should  be  reckoned  among  the  unicellular 
Algae  or  among  the  Protozoa,  but  this  controversy  is  now  practi- 
cally over,  and  biological  disquisitions  upon  the  group  are  equally 
at  home  and  equally  necessary  in  zoological  and  botanical  treatises 
and  journals. 

When  an  organism  possesses  a  green  colour,  due  to  the  presence 
of  chloroplasts  stained  with  chlorophyll,  has  a  cell-wall  that  gives 
the  chemical  reactions  of  cellulose,  and  is  devoid  of  a  mouth  for  the 
ingestion  of  solid  food,  it  is  usually  regarded  as  a  plant.  When, 
on  the  other  hand,  an  organism  bears  no  chlorophyll,  has  no  cell- 
wall,  or  has  a  cell-wall  that  does  not  give  the  cellulose  reaction, 
and  possesses  a  mouth  for  the  ingestion  of  solid  food,  it  is  usually 
regarded  as  an  animal. 

If  it  were  possible  to  divide  the  Mastigophora  into  two 
divisions,  one  containing  all  those  forms  provided  with  a  mouth 
and  devoid  of  chlorophyll  and  a  cellulose  cell-wall ;  and  the  other 
containing  all  those  forms  without  a  mouth,  bearing  chlorophyll  and 
surrounded  by  a  cellulose  cell-wall,  then  the  former  division  could 
be  assigned  to  the  animal  kingdom  and  the  latter  to  the  vegetable 
kingdom.  Such  a  division  would,  however,  be  thoroughly  un- 
scientific and  unnatural.  It  could  only  be  made  by  deliberately 
ignoring  obvious  genetic  relationships.  Moreover,  such  a  division 
would  leave  out  of  account  a  number  of  organisms — particularly 
Monadidea — which  fail  to  fulfil  all  the  conditions  for  their  admission 
into  either  of  the  divisions. 

It  is  not  by  the  study  of  any  one  stage  of  the  life-history  of 
these  organisms  that  it  is  possible  to  arrive  at  any  clear  conception 
of  the  best  distinction  that  can  be  drawn  between  the  animal  and 
vegetable  kingdoms. 

The    study  of  the  whole   life -history   of  some    of   the   lower 


animals  and  plants,  however,  suggests  a  line  of  distinction  which  is 
perhaps  more  in  accordance  with  a  natural  system  of  classification. 

In  the  life -history  of  Ulothrix,  one  of  the  Ulotrichaceae,  an 
example  of  an  organism  that  is  universally  regarded  as  a  plant,  we 
find  two  forms  of  cells.  There  are  the  cells  of  the  filamentous 
thallus,  protected  by  a  cell-wall,  containing  chlorophyll,  and,  under 
favourable  conditions,  growing  and  increasing  in  number  by  fission ; 
and  there  are  the  cells  provided  with  two  or  four  flagella  that 
escape  from  their  cellulose  investments  and  eventually  conjugate  to 
form  a  motionless  zygospore. 

If  we  compare  this  with  the  life-history  of  such  a  form  as 
Mastigella,  one  of  the  Mastigophora  that  is  universally  regarded  as 
an  animal,  we  find  that  during  the  phase  of  life  when  growth  and 
repeated  multiplication  by  fission  occurs  the  organism  is  actively 
moving  about  by  means  of  its  flagellum  or  its  pseudopodia,  and  that 
the  gametes  that  it  gives  rise  to  are  also  active  and  flagellate. 
Any  period  in  the  life-history  of  Mastigella  when  active  movements 
cease  is  not,  as  in  the  case  of  Ulothrix,  a  period  of  vegetative 

If  we  regard,  then,  as  marks  of  distinction  between  an  animal 
and  a  plant  (1)  that  the  stage  of  growth  and  reproduction  of 
somatic  cells  by  fission  is  marked  by  a  period  of  active  mobility  in 
the  former,  and  of  stability  in  the  latter ;  and  (2)  that  the  flagellate 
cells  of  the  latter  do  not  grow  and  divide  by  fission,  but  conjugate 
and  give  rise  immediately  to  a  sedentary  zygospore,  whereas  in  the 
former  the  flagellate  cells  may  grow  and  divide  by  fission,  we 
represent  a  consideration  which  has  had  considerable  weight  in 
determining  the  action  of  zoologists  in  including  the  Mastigophora 
in  the  animal  kingdom.  But  the  boundary  thus  drawn,  even  if  it 
is  the  best  that  can  be  drawn,  is  itself  subject  to  some  exceptions. 

In  some  of  the  Chlamydomonadina  we  find,  for  example,  that 
flagellate  individuals  similar  in  general  characters  to  the  gametes 
form  a  gelatinous  investment,  withdraw  their  flagella,  grow  and 
divide  repeatedly  by  fission.  It  is  difficult  to  distinguish  this  phase 
of  life  (the  "  palmella-stage,"  as  it  is  called)  from  a  true  plant  under 
the  terms  of  our  definition.  The  close  relation  of  the  Chlamy- 
domonadina to  the  Chromomonadina,  however,  is  so  clear  that  to 
separate  them  by  placing  one  order  in  the  vegetable  kingdom  and 
the  other  in  the  animal  kingdom  on  this  ground  alone  would  be 

The  life-history  of  the  Chlamydomonadina  seems  to  support 
very  strongly  the  view  that  some  of  the  families  of  the  lower  Algae 
have  sprung  from  a  flagellate  ancestry,  but  it  does  not  justify  the 
assumption  that  the  vegetable  kingdom  as  a  whole  owes  its  origin 
to  the  class  Mastigophora.1 

1  See  Blackman  and  Tansley  (2),  and  West  (22,  pp.  32  et  seq.). 


It  is  principally  in  respect  of  their  modes  of  nutrition  that  the 
Mastigophora  appear  to  betray  the  mixed  animal  and  vegetable 
properties,  so  that  as  a  class  they  have  come  to  be  regarded  as 
mixotrophic  micro-organisms.  The  four  possible  methods  of  ali- 
mentation— holozoic,  parasitic,  saprophytic,  and  holophytic — are  all 
to  be  met  with  among  the  members  of  this  protean  series,  either 
separately  or  in  combination.  When  a  single  species  can  vary  its 
metabolism  in  adaptation  to  its  immediate  environment,  for  example, 
according  as  it  is  exposed  to  or  deprived  of  the  influence  of  light, 
it  is  said  to  be  mixotrophic  in  the  strict  sense  of  the  term  (Pfefl'er). 

It  is  not  always  easy  to  assert  positively  in  Avhat  manner  food  is 
conveyed  into  the  protoplast  (protoplasmic  body  of  the  cell),  but  it 
is  certain  that  holozoic  nutrition  is  often  associated  in  the  same 
species  with  saprophytic  (Monadidea),  saprophytic  with  parasitic, 
saprophytic  with  holophytic  (Euglenoidea),  and,  more  rarely, 
holozoic  with  holophytic  (Chromulina).  Sometimes  three  methods 
are  found  in  combination — holozoic,  saprophytic,  and  holophytic 
(Ochromonas).  It  may  be  stated  as  a  general  rule  that  all  Lisso- 
flagellata  (i.e.  true  Flagellata  in  the  restricted  sense)  are  capable  of 
saprophytic  nutrition,  that  is  to  say,  of  absorbing  nutriment  from 
putrescent  substances  in  an  aqueous  medium,  but  that  this  source 
of  food  is  usually  accessory  to  some  other  essential  means  of 
nourishment.  Where  saprophytism  is  the  sole  condition  of  exist- 
ence, as  in  the  case  of  the  Astasiina,  there  is  reason  to  regard  it 
as  a  secondary  state  derived,  in  the  particular  instance  quoted, 
from  a  condition  of  holophytism. 

The  parasitic  forms  may  be  described  broadly  as  falling  inta 
three  categories  :  ectoparasites  (Costia,  Stylochrysalis,  Silicoflagellata) ;. 
endoparasites  (species  of  Hexamitus,  Megastoma,  Tetramitus,  Tricho- 
mastix,  Trichomonas,  Trichonymphidae) ;  and  haematozoa  (Trypano- 
soma,  Herpetomonas). 

The  non-parasitic  Mastigophora  are  either  free -swimming  or 
sessile,  solitary  or  colonial  in  habit. 

Some  species  are  capable  of  temporary  fixation  by  means  of  a, 
protoplasmic  stalk  either  of  pseudopodial  (e.g.  Oicomonas  sp.,  Fig.  5 
(31))  or  of  flagellar  (e.g.  Bodo  sp.)  origin.  Some  solitary  free  forms- 
are  closely  related  to  solitary  fixed  forms  (e.g.  Euglena,  and  Ascoglena), 
and  many  free-swimming  colonial  genera  have  sessile  representatives- 
(e.g.  Dinobryon  and  Hyalobryori). 

The  form  of  association  of  individuals  in  the  colonies  varies 
within  limits,  and  there  is  a  great  amount  of  parallelism  in  this 
respect  between  members  of  different  orders.  An  entire  colony  or 
coenobium  may  attain  to  a  certain  degree  of  individuation,  which  is 
most  marked  in  the  Volvocina,  but  is  not  wanting  in  other  groups, 
as  is  evident  from  the  co-ordinated  movements  which  they  execute 
and  from  the  fact  that  the  whole  coenobium  may  undergo  binary 


fission  (Uroglena).  On  the  other  hand,  the  units  often  retain  a 
facultative  independence,  and  the  coenobium  may  then  undergo 
dissociation  (Synura). 

The  principal  forms  of  association  of  individuals  are  the  follow- 
ing : — 1.  Linear  aggregates,  e.g.  Hirmidium,  Chlorodesmus,  Ceratium; 

2.  Rosettes,  e.g.  Bicosoeca  socialis,  Cydonexis  annularis,  Gonium  pedorale ; 

3.  Plates,  e.g.  Proterospongia,  Platydorina ;  4.  Spherical  aggregates,  e.g. 
Sphaeroeca,  Uroglena,  Volvox ;  5.  Dendroid  associations,  e.g.  Dinobryon, 
Hyalobryon,  Poteriodendron,  Anthophysa,  Ehipidodendron,  Dendromonas, 

Of  the  above  colonial  assemblages  it  is  to  be  remarked  that  the 
dendroid  form  is  the  most  polymorphic  in  actual  appearance.  As 
for  transitional  forms,  it  is  not  difficult  to  construct  a  series,  while 
analogies  are  stupefying  in  their  abundance.  Thus  a  biserial  linear 
aggregate  like  Chlorodesmus  in  comparison  with  a  rosette  like  Cydo- 
nexis is  absolutely  paralleled  by  species  of  the  pelagic  Ascidian,  Salpa. 
A  transition  from  a  rosette  to  a  plate  is  afforded  by  Gonium,  and 
from  a  rosette  to  a  spherical  aggregate  by  the  volvocine  genus 
Stephanosphaera,  in  which  the  units  are  arranged  in  a  rosette 
though  surrounded  by  a  common  gelatinous  envelope. 

The  Mastigophora  as  a  class  may  be  defined  broadly  as  uni- 
nucleated  Protista  which  perform  their  movements  by  means  of  one, 
two,  or  several  flagella,  usually  arising  at  or  near  the  anterior  end, 
i.e.  the  end  which  is  directed  forwards  during  locomotion.  The  typical 
motion  of  the  flagellum  has  been  described  as  one  of  circumduction 
(Delage),  by  which  the  cell  is  drawn  along  at  the  same  time  that 
it  rotates  about  its  axis.  The  flagellum  of  a  typical  Flagellate 
Infusorian  is  therefore  a  tractellum,  as  opposed  to  the  tail  of  a 
spermatozoan,  which  is  a  pulsellum.1  It  acts,  however,  as  a  pulsellum 
in  exceptional  cases  among  the  Monadidea,  and  with  the  Choano- 
flagellata  when  they  quit  their  attachment  in  order  to  effect  change 
of  position. 

According  to  the  number,  position,  and  proportions  of  the 
flagella  we  recognise  monomastigote  forms,  with  a  single  porrect 
flagellum ;  paramastigote,  with  one  or  two  small  accessory  flagella  at 
the  base  of  the  main  one ;  isomastigote,  with  from  two  to  four  equal 
flagella ;  heteromasligote,  with  divergent  flagella,  one  directed  forwards 
or  transversely,  the  other  directed  backwards ;  polymastigote,  with 
more  than  four  flagella ;  to  which  may  be  added  holomastigote  forms, 
with  numerous  flagella  distributed  over  the  entire  surface  of  the 
cell.  The  disposition  of  the  flagella  has  a  distinct  systematic 
importance,  but  of  much  more  limited  application  than  was  formerly 

1  The  terms  "  tractellum  "  and  "  pulsellum  "  were  suggested  by  Prof.  Lankester. 
In  some  elongate  metabolic  species  (Astasiina)  the  tractellum  is  directed  straight 
forwards,  and  only  the  apical  portion  of  it  executes  rapid  vibrations,  drawing  the  body 
.along  without  rotation. 


supposed,  since  the  phenomenon  of  parallelism  is  as  strikingly  dis- 
played in  this  respect  as  in  the  manner  of  formation  of  colonies. 

The  heteromastigote  condition  merits  particular  notice  since  it 
characterises  an  entire  sub -class  (Dinoflagellata),  where  the  one 
flagellum  is  transverse,  usually  lying  in  an  annular  depression,  while 
the  other  is  longitudinal  and  is  also  partially  protected  by  a  groove, 
but  extends  backwards  freely  (Fig.  10).  This  is  a  special  mani- 
festation of  the  heteromastigote  condition,  but  equally  interesting 
examples  occur  in  many  families  of  Lissoflagellata,  where  the 
anterior  flagellum  is  normally  directed  forwards  (tractellum)  and 
the  posterior  flagellum  which  arises  from  the  body  of  the  cell  close 
to  the  former  is  trailed  behind.  The  posterior  flagellum  in  these 
cases  exerts  a  directive  and  modifying  influence  upon  the  move- 
ments of  the  Infusorian,  serving  also  as  an  anchor  and  sometimes  as 
a  spring  promoting  a  rapid  jerking  movement  of  leaps  and  bounds 
like  the  tail  of  a  Podurid. 

The  posterior  flagellum  of  heteromastigote  Mastigophora  may 
be  aptly  described  as  a  gubernaculum  (Fig.  7  (10))  and  referred  to  by 
that  term. 

The  flagellum  is  usually  so  extremely  attenuated  that  it  is 
very  difficult  to  discover  any  structure  in  it,  but  as  its  base 
may  often  be  traced  from  the  surface  through  the  ectoplasm  to  the 
endoplasm,  it  seems  probable  that  it 
consists  of  an  axial  filament  derived 
from  the  endoplasm  and  a  delicate 
cortical  sheath  derived  from  the  ecto- 
plasm. It  is  interesting  to  note  that 
in  the  Ehizomastigoda  there  is  an 
endoplastic  axial  filament  in  the  pseudo- 
podia  (Fig.  1).  It  is  impossible  to 
draw  any  morphological  line  of  dis- 
tinction between  a  flagellum  and  a 
cilium,  and  in  the  Lophomonadina,  for 
example,  the  vibratile  processes  have  Fia  *• 

been    interpreted    as   flagella  by  those  Anffl^ofS'SUlS 
who   regard    this   group   as   belonging  g^£5&£  ffi£  5£SS?K! 

to  the  Mastigophora  and  as  cilia  by  («*)<*  the  pseudopodia  (ps);/,  flagel- 
.1  i  j  •,  •  M  •  lum ;  pd,  pellicle ;  B,  flagellar  reser- 

those  who  regard  it  as  a  family  of  voir.  x  eso.  (After  Goidschmiut.) 
Infusoria.  Since  the  discovery  that 

the  equatorial  groove  of  the  Dinoflagellata  (p.  182)  is  not  ciliated,  it 
is  usually  regarded  as  a  character  of  the  class  that  true  cilia  do  not 
occur ;  and  if  the  vibratile  processes  of  the  Polymastigina  are  true 
flagella,  the  only  exception  to  this  is  to  be  found  in  the  aberrant 
genera  Pteridomonas,  Maupasia,  and  Monomastix  (pp.  164  and  170). 
As  a  rule,  there  seems  to  be  no  connection  between  the  base  of 
the  flagellum  and  the  nucleus,  but  such  a  connection  can  be  traced 



cst.  --, 


in  the  genera  Mastigamoeba  and  Mastigina,  recalling  the  relation  of 
the  axial  filament  to  the  nucleus  in  certain  Heliozoa  (p.  23). 

At  the  base  of  the  axial  filament  there  is  sometimes  found  a 
minute  granule,  with  peculiar  staining  properties,  known  as  the 
blepharoblast  (Fig.  2,  b),  and  closely  associated  with  this  there  is 
in    the    Trypanosomata l    a    small    detached 
portion  of  the  nucleus  known  as  the  "kineto- 

At  the  base  of  the  flagellum  there  is  often 
found  a  special  vacuole  into  which  the  con- 
tractile vacuoles  may  or  may  not  open  (Figs. 
1  and  2).  This  is  the  flagellar  reservoir. 
In  some  forms  (Trichomonas  and  Trypanoso- 
mata) a  delicate  undulating  membrane  is 
found  at  one  side  of  the  flagellum  (Fig.  2, 
p.  195). 

Besides  the  flagellate  movements  there  are 
two  other  important  ways  by  which  locomotion 
can  be  effected  by  certain  species,  namely,  by 
amoeboid  and  by  so-called  metabolic  or  euglenoid 
changes  of  shape,  the  former  resulting  in  the 
protrusion  of  pseudopodia,  and  the  latter 
involving  alternate  protraction  and  contraction 
of  the  body,  as  may  be  observed  in  many 
worms  (Fig.  5  (28)). 

The  possibility  of  executing  amoeboid  and 
ture  of  Copromonas.     b,  metabolic    movements    depends    largely   upon 

blepharoblast;    c.p,    cyto-  .  »    J        ? 

pharynx;,  cytostome ;  the  nature  of  the  integument  or  pellicle  which 
/I,"'  flageiuTm^6 /.»,aCfood-  protects  the  protoplast  from  the  surrounding 

vacuoles;  N,  nucleus;  R,    fl,-,;/)  rnpHium 
flagellar  reservoir.     (After    r  lln- 

Dobeii.)  There  are  three  principal  kinds  of  integu- 

ment, with  many  degrees  of  differentiation  : — 

1.  Periplast. — This  is  an  integral  portion  of  the  protoplast,  from 
which  it  is  never  separated  and  with  which  it  divides.     In  naked 
cells,  such  as  Mastigamoeba,  it  appears  as  a  simple  ectoplasm  covered 
by  a  very  thin  pellicle  (Fig.  I, pel),  or  as  an  alveolar  layer  of  proto- 
plasm (Multidlia).     In  most  cases  there  is  a  more  or  less  well- 
defined  pellicle  or  plasmatic  membrane,  which  may  be  distinguished 
under  the   name   of  proteid-membrane.     This  achieves  its   highest 
development  in  the  Euglenoidea,  where  it  often  presents  a  spirally 
striated  structure  and  resists  decomposition  (Fig.  5  (16,  17)). 

2.  Perisarc. — The  perisarc  does  not,  as  a  rule,  form  an  integral 
part  of  the  protoplast,  and  does  not  usually  divide  with  it,  so  that 
after  the  division  of  the  protoplast  one  of  the  fission-products  issues 

1  For  a  discussion   of  the  relations   of  these   structures  compare  Dobell  (3), 
Minchin  (13),  Moore  (14),  Hartman  and  von  Prowazek  (5). 

Fio.  2. 
Diagram  of  the  struc- 


from  the  perisarc  as  a  naked  cell.  The  protoplast  is  never  com- 
pletely adherent  to  its  perisarc,  but  is  capable  of  more  or  less 
independent  movement  within  it,  and  recedes  from  it  upon  the 
formation  of  the  resting-stage,  and  also  in  consequence  of  plasmo- 
lysis.  Its  chemical  composition  is  based  upon  a  gelatinous  substance 
of  carbohydrate  nature,  and  in  Dinobryon  Klebs  has  found  that  the 
perisarc  gives  the  typical  cellulose  reaction. 

The  periplast  is  always  present  in  Lissoflagellates,  but  the 
perisarc  is  a  secondary  formation  secreted  by  the  protoplast  through 
the  periplast,  and  may  or  may  not  be  present. 

The  perisarc  may  occur  as  a  capsule  closely  investing  the  cell 
with  an  apical  opening  for  the  flagellum,  as  in  Chrysococcus  and 
Trachelomonas.  In  the  Chrysomonadine  genera  Synura,  Mallomonas, 
Hymenomonas,  and  Microglena  the  protoplast  is  closely  adherent  to 
the  perisarc,  which  here  tends  in  the  direction  of  a  true  cell-wall 
and  is  called  a  cuticle.  In  Hymenomonas  by  exception  the  perisarc 
divides  with  the  cell. 

The  most  familiar  form  in  which  the  perisarc  is  developed  is 
that  of  a  cupule,  as  in  the  calyptoblastic  Hydroids.  Well-known 
examples  of  cupule-formation  are  presented  by  the  genera  Bicosoeca, 
Poteriodendron,  Salpingoeca  (Fig.  7  (6, 7)),  Dinobryon,  etc.  Some  genera 
secrete  a  stalk  only,  Avithout  a  cupule,  of  which  AntJwphysa  and 
CephalotJwmnion  are  among  the  best-known  examples. 

3.  'Cell- Wall. — This  stands  in  intimate  relation  with  the  proto- 
plast, as  in  Algae  and  higher  plants,  so  that  the  cell-body  has  no 
independent  movement,  apart  from  the  automatic  streaming  of 
granules.  The  cell-wall  may  (Dinoflagellata)  or  may  not  (Volvo- 
caceae  and  Coccolithophoridae)  divide  with  the  protoplast.  Its 
chemical  composition  resembles  that  of  the  perisarc,  and  in  the  Dino- 
flagellata consists  of  cellulose.  In  the  Coccolithophoridae  the  cell- 
wall  is  built  up  of  several  shells 
composed  of  calcium  carbonate. 

Nucleus. — The  nucleus  of  the 
Mastigophora  shows  many  varie- 
ties of  intimate  structure.  In  .A. 
some  cases  the  chromatin  is  dis- 
tributed  in  the  form  of  a  simple 
.chromatic  network  (Herpeto- 
monas),  in  others  (Bodo,  Copro- 
monas,  Fig.  2)  the  chromatin  is 

nrptjpnr    in    flip  fnrm   nf    n   opnfril  Two  sta8es  in  the  mitosis  of  the  nucleus 

mtrai  of  xoctnuca  mmaris.     A,  archoplasmic  body 

lump  Or  maSS.       In  Eugkna  there  <a>  becoming  elongated  previous  to  division  ; 

•  •_..«                                        i  w>  nucleus.    B,  the  nucleus  has  wrapped  round 

IS  Within    the    nuclear    membrane  the  central  part  of  the  archoplasmic  body,  and 

i              ,  •                                 i  the    chromosomes  (ch)   are   approaching   the 

separate   chromatin  masses,  and   poies  in  rows.   (After  CWklm.) 

in   addition  a    substance    which 

has   been    variously   interpreted,    but    is   usually   known    as    the 


"  nucleolar  centrosome."  In  Noctiluca  (Fig.  3)  an  archoplasmic 
body  situated  outside  the  membrane  accompanies  the  nucleus  and 
gives  rise  to  the  achromatic  spindle  of  the  mitotic  figure.  Mitotic 
division  of  the  nucleus  has  been  described  in  a  large  number  of 
cases  taken  from  all  the  principal  divisions  of  the  group,  but  itv  is 
certain  that  in  some  cases  nuclear  division  occurs  by  amitosis 
(Copromonas  and  others,  Dobell  [3]).  Nuclear  reduction  in  the  for- 
mation of  the  gametes  has  been  observed  in  some  cases  (Trichomonas, 
Bodo,  Hexamitus,  Copromonas,  and  others). 

Notwithstanding  the  great  variety  of  structure  and  mode  of 
division  of  the  nuclei  in  the  Mastigophora,  there  is  no  evidence  that 
in  any  case  a  division  of  the  nuclear  substance  takes  place  into  a 
somatic  nucleus  and  sexual  nucleus,  comparable  with  the  mega- 
nucleus  and  micro-nucleus  of  the  Infusoria  (Heterokaryota).  The 
separation  of  the  kineto-nucleus  from  the  main  nucleus  in  the 
Trypanosomata  may  suggest  that  in  this  case  there  is  a  delegation 
of  special  functions  in  connection  with  the  flagellum  to  a  detached 
portion  of  the  nucleus ;  but  apart  from  this  all  the  Mastigophora 
are  in  the  strictest  sense  Homokaryota  (Hickson). 

The  life -history  of  the  organisms  comprised  by  the  class 
Mastigophora  shows  so  many  varieties  that  no  general  principles 
can  be  laid  down  in  this  place.  The  life-histories  of  several  forms 
are  described  in  the  account  given  of  the  various  subdivisions  of 
the  group.  The  great  advance  in  our  knowledge  of  these  forms 
that  has  been  made  during  the  past  few  years  suggests  that  a 
process  of  gametogenesis  followed  by  conjugation  of  the  gametes 
occurs  in  the  life-histories  of  all  the  orders. 

The  Mastigophora  are  an  important  component  of  the  micro- 
plankton  of  oceanic  and  lacustrine  waters.  The  Dinoflagellata 
together  with  the  Algae  of  the  natural  order  Bacillariaceae,  to  which 
the  former  appear  to  be  more  or  less  closely  related,  are  said  to 
constitute  the  bulk  of  the  primary  food-supply  (Urnahrung)  of  the 
sea  [Schiitt], 

It  is  customary,  in  the  more  recent  treatises,  to  employ  the 
term  Flagellata  in  a  restricted  sense,  equivalent  to  the  Lissoflagellata 
of  Lankester,  with  the  inclusion  of  the  Choanoflagellata.  In  this 
sense  also  the  term  Euflagellata  has  been  employed,  and  the 
flagellate  members  of  the  freshwater  plankton  comprise  Euflagellate, 
Dinoflagellate,  and  Phytoflagellate l  forms.  The  marine  plankton 
comprises  in  addition  the  Cystoflagellata  and  the  Coccolitho- 

It  is  in  order  to  avoid  possible  confusion  that  the  term  Mastigo- 
phora, introduced  by  Diesing  in  1866,  is  employed  to  designate  the 
entire  group  of  flagellate  organisms. 

1  Sometimes  the  Phytoflagellata  are  comprehended  within  the  Euflagellata,  but 
this  tends  to  misapprehension. 


The  six  sub-classes  of  Mastigophora  may  be  tabulated  as 
follows  : — 

Sub-Class  1.  Lissoflagellata      )  -,-,  a      ,,  , 

«,  >  Luflasjellata. 

„         2.  Choanoflagellata  j 

„  3.  Phytoflagellata  (Volvocaceae). 

„  4.  Dinoflagellata  (Peridiniales). 

,,  5.  Cystoflagellata. 

,,  6.  Silicoflagellata. 

The  Euflagellata  are  defined  as  Protozoa  which  possess  a  sharply 
defined,  uninuclear  sarcode,  whose  periplast  is  either  a  simple 
ectoplasm  or  a  definite  pellicle.  During  the  greater  portion  of 
their  life  they  are  in  motion,  or  at  least  capable  of  motion.  They 
have  a  definite  anterior  end,  from  which  one,  two,  or  many  flagella 
arise,  and  they  possess  one  contractile  vacuole  or  several.  Repro- 
duction takes  place  by  simple  longitudinal  fission,1  generally  in  the 
flagellate  condition,  sometimes  in  a  resting  condition.  It  seems 
probable  that  most  of  the  Euflagellata  are  capable  of  forming 
resistent  cysts,  usually  called  sporocysts. 

The  occurrence  of  a  process  of  conjugation  was  asserted  by 
Dallinger  and  Drysdale  and  others  of  the  earlier  observers,  but 
some  doubt  was  thrown  upon  the  accuracy  of  these  statements  by 
Biitschli  and  Senn.  In  recent  years,  however,  the  formation  of 
definite  gametes  and  a  process  of  conjugation  have  been  proved 
to  occur  in  Mastigella  by  Goldschmidt  (4),  in  Pseudospora  by 
Kobertson  (18),  in  Monas  and  Bodo  by  von  Prowazek  (16),  in 
Copromas  by  Dobell  (3),  and  in  Trypanosoma  and  other  forms  by 
Schaudinn  (19).  There  seems  to  be  little  doubt,  therefore,  that 
conjugation  is  a  normal  process  in  the  life-history  of  all  the 


The  members  of  this  sub-class  are  distinguished  from  the  other 
Euflagellata  by  the  absence  of  a  collar.  The  sub -class  is  divided 
into  the  three  orders  : 

1.  Monadidea. 

2.  Euglenoidea. 

3.  Chromomonadidea. 

ORDER  1.  Monadidea,  Biitschli. 

The  Monadidea  comprise  the  least  differentiated  forms  of 
Mastigophora,  and  include  genera  that  exhibit  affinities  with  the 
Proteomyxa  (Multicilia,  Pseudospora,  p.  8),  with  the  Lobosa  (Rhizo- 

1  Cases  of  true  transverse  fission  are  very  rare  among  the  Lisso-  and  Choano- 
flagellates  ;  e.g.  Oxyrrhis,  Stylochrysalis,  Phalansterium. 



mastigoda),  and  possibly  also  with  the  Heliozoa  (Dimorpha).  They 
are  colourless  Flagellata  with  one  to  an  indefinite  number  of  flagella, 
a  simple  vacuole  system,  and  usually  a  single  nucleus.  Their 
nutrition  may  be  holozoic,  parasitic,  or  saprophytic,  but  probably 
never  holophytic. 


Solid  foodtmay  be  ingested  at  all  points  in  an  amoeboid  fashion. 
StrB-TRiBE  1.  HOLOMASTIGODA,  Lauterborn.      With  polyaxonic  body, 
flagella  scattered  all  over  the  surface,  pseudopodial  ingestion  of  food,  loco- 
motion rotatory,  defaecation  at  all  points. 

Multicilia,  Cienkowski  ;  M.  marina,  Cienk.,  with  one  nucleus  ;  M. 
lacustris,  Lauterborn,  plurinuclear,  the  only  instance  of  the  kind  among 
Mastigophora.  The  genus  Grassia,  Fisch.,  closely  allied  to  Multicilia,  is 
found  in  the  alimentary  canal  of  the  frog  and  in  the  blood  of  Hyla. 

SUB-TRIBE  2.  KHIZOMASTIGODA,  F.  E.Schultze.  With  one  or  two  flagella, 
natant  and  amoeboid  or  heliozooid  phases.  The  flagella  persist  through 
the  amoeboid  or  heliozooid  phase.  The  monomastigote  and  dimastigote 
genera  present  a  parallel  series,  and  in  addition  there  is  an  aberrant  genus. 
Pteridomonas,  Penard,  in  which  there  is  a  circlet  of  8-12  cilia,  which  can 
be  rolled  inwards  like  a  watch-spring  and  then  bent  outwards,  exerting  a 
jerking  action  by  which  the  animal  hops  backwards. 
These  cilia  surround  the  base  of  the  single  main 

In  the  genus  Mastigamoeba  the  flagellum  arises 
directly  from  the  nucleus.  The  genus  Mastigina 
(Frenzel)  is  closely  related  to  Mastigamoeba,  but  the 
body  is  covered  with  a  thick  pellicle.  The  position 
of  Mastigella,  Frenzel  (Fig.  4),  is  more  difficult  to 
determine,  as  there  may  be  one  or  more  flagella 
which  are  quite  independent  of  the  nucleus.  In 
Mastigamoeba  schulzei  (Frenzel)  and  Mastigina  setosa 
(Goldschmidt)  the  body  is  thickly  beset  with  long 
rigid  bristles  which  have  the  general  appearance 
of  cilia,  but  seem  to  have  the  same  nature  as  the 
adhesive  granules  (Klebkdrner)  with  which  the 
pellicle  and  superficial  ectoplasm  of  several  species 
of  the  three  genera  are  provided.  It  is  possible 
that  they  are  of  the  same  nature  as  the  spicules 
of  the  ectoplasm  found  in  several  of  the  Lobosa 
Mastigella  vitrea,  Gold-  (Trichosphaerium,  etc.)  and  some  of  the  Heliozoa 

schmidt.  OneoftheRhizo-  )  2  '  ~n    ao\ 

mastigoda.     Active  form.  (Heterophrys    (ct.  pp.  23,  68). 

c.»,    contractile    vacuole ; 

/.  portions  of  filamentous  m,         i-r      v»  i.  r     -nr     ,  •     77          •  ,    •         i 

algae  ingested  as  food ;  fl,  Ine  liie-nistory  of  Mastigella  vitnna  has 
ScTmidto250-  (After  recently  been  fully  investigated  by  Gold- 
schmidt  (4).  During  the  vegetative  life  of 
this  animal  a  series  of  binary  fissions  occur  which  are  preceded 
by  a  withdrawal  of  the  pseudopodia  and  flagellum  and  a  mitotic 

Fio.  4. 


division  of  the  nucleus.  The  number  of  chromosomes  seen  in  these 
mitotic  divisions  is  about  40,  and  there  are  no  centrosomata  at 
the  poles  of  the  spindle.  The  sexual  reproduction  is  preceded 
by  the  formation  of  mega-  and  microgametocytes.  In  the  early 
stages  the  gametocytes  cannot  be  distinguished  from  the  ordinary 
vegetative  individuals  except  as  regards  the  microscopic  character 
of  the  nuclei.  A  number  of  minute  granules  of  chromatin 
(chromidia  or  sporetia  of  Goldschmidt)  are  extruded  from  the- 
nucleus,  increase  in  number  and  size,  and  give  rise  to  the  nuclei 
of  the  numerous  gametes.  The  cytoplasm  of  the  gametes  is 
formed  by  a  differentiation  of  clear  protoplasm  around  each 
nucleus.  In  the  case  of  the  formation  of  the  megagametes  at  least 
one  mitotic  division  of  the  nucleus  occurs,  which  has  been  inter- 
preted to  be  a  polar  division.  A  similar  polar  division  of  the 
nucleus  probably  takes  place  also  in  the  formation  of  the  micro- 
gametes.  The  elements  of  these  nuclei  are  so  small  that  it  has 
not  been  proved  that  a  definite  reduction  in  the  number  of  the 
chromosomes  occurs.  In  both  kinds  of  gametocytes  an  encystment 
accompanied  by  withdrawal  of  the  pseudopodia  and  flagella  occurs, 
but  the  microgametocyte  encysts  sooner  than  the  megagametocyte. 
The  gametes  escape  from  the  gametocytes  and  conjugate  to  form 
a  zygote.  The  megagametes  are  about  3-6  /*  in  diameter  and 
are  provided  with  a  single  flagellum  15-18  /A  in  length.  The  micro- 
gametes  are  2-8  /*  in  diameter  and  are  also  provided  with  a 
flagellum.  The  zygote  is  a  minute  active  monad,  which  divides 
several  times  by  simple  fission  and  then  grows  and  assumes  the 
general  characters  of  the  genus. 

The  principal  genera  are  : — Amoeboid  and  monomastigote  :  Mastiga- 
moeba,  Schulze  ;  Mastigella,  Frenzel  ;  Mastigina,  Frenzel.  Amoeboid  and 
dimastigote  :  Cercobodo,  Kent  =  Dimastigamoeba,  Blochmann,  and  some  of 
the  species  attributed  to  the  genus  Cercomonas  (Fig.  5  (32,  33)).  Heliozooid 
and  monomastigote  :  Actinomonas,  Kent.  Heliozooid  and  dimastigote  : 
Dimorpha,  Gruber. 

TRIBE  2.  PROTOMASTIGINA  (sensu  stricto). 

Solid  food  is  ingested  at  a  fixed  point  near  the  base  of  the  flagellum. 

SUB-TRIBE  1.  MoxoMASTiGODA.1  A.  Flagellum  directed  forwards, 
a.  Oicomonas,  Kent  (Fig.  5  (29,  30,  31)).  Ingestion  of  food  at  base  of 
flagellum  by  means  of  a  protuberant  vacuole  (vacuolar  ingestion)  which 
subsequently  migrates  to  the  posterior  end.  /3.  Leptomonas,  Kent.  Rod- 
shaped  or  fusiform,  parasitic  in  intestine  of  insects.  B.  Flagellum 
directed  backwards,  a.  Ancyromonas,  Kent.  The  single  flagellum  arises 
at  anterior  end,  but  is  bent  backwards  and  serves  as  an  anchor  or 

1  Tdis  sub-tribe  comprises  the  Cercomonadina  of  Saville  Kent  or  the  Oicomona- 
daceae  of  Senn.  From  the  work  of  Klebs  and  others  it  seems  necessary  to  reject 
the  genus  Cercomonas,  since  the  confusion  surrounding  it  cannot  lie  lightened. 


gubernaculum  as  in  Bodo.  Marine.  (3.  Phyllomonas,  Klebs.  A  triangular, 
contorted,  foliaceous  monad  with  the  flagellar  pole  directed  backwards 
in  locomotion ;  the  flagellum  acts  therefore  as  a  pulsellum.  Stagnant 
water.  C.  Sessile,  calyptoblastic  genera,  a.  Codonoeca,  Clark,  constructs 
a  pedunculate,  ribbed,  colourless  theca  in  which  it  resides  freely. 
Freshwater  and  marine.  (3.  Platytheca,  Stein,  constructs  a  membranous 
encrusting  theca. 

The  Family  TRYPANOMORPHIDAE,  containing  the  single  genus  Try- 
panomorpha,  Woodcock,  belongs  to  this  sub-tribe.  A  full  description  of 
this  form  is  given  in  Section  G,  p.  193. 

Fio.  5.' 

1,  Chlamydomonas  pidvisculus,  Ehrb.  ;  one  of  the  Phytoflagellata ;  free-swimming  indivi- 
dual ;  a,  nucleus  ;  bb,  contractile  vacuoles  ;  c,  pyrenoid  ;  d,  cellulose  investment ;  e,  stigma 
(eye-spot).  2,  resting-stage  of  the  same  with  fourfold  division  of  the  cell -con  tents ; 
letters  a>  before.  3,  a  cyst  that  has  been  formed  by  the  conjugation  of  gametes  and  is  now 
liberating  a  large  number  of  minute  biflagellate  zooids.  4,  Synerypta  volvox,  Ehrb.  ;  one  of  the 
Chrysomonadina.  A  colony  enclosed  by  a  mucilaginous  test(c).  a,  stigma  ;  fr,  vacuole.  5,Uroglen« 
volvox,  Ehrb. ;  one  of  the  Chrysomonadina.  Half  of  a  large  colony.  6,  Chlorogoniiim  euchlorum, 
Ehrb.  ;  one  of  the  Phytoflagellata  ;  a,  nucleus  ;  b,  contractile  vacuoles  ;  c,  pyrenoids  ;  (?)  d,  eye- 
spot.  7,  the  same  species,  showing  conjugation  of  the  gametes.  8,  a  colony  of  Dinobryon  sertularia, 
Ehrb.  ;  one  of  the  Chrysomonadina  loricata,  x  200.  9,  Sphaerella  pal u stria,  Girod  (  —  Haemato- 
coccus  fxilustris) ;  one  of  the  Chlainydomonudina ;  ordinary  individual  with  widely  separated 
test,  to  which  it  is  attached  by  delicate  strands  of  protoplasm,  not  shown  in  the  figure ; 

a,  nucleus ;  b,  contractile  vacuole  ;  c,  pyrenoid.     10,  dividing  resting-stage  of  the  same.     11,  a 
gamete  of  the  same.    12,  Phalansterium  consociatum,  Cienk.  ;  one  of  the  Choanoflagellata,  x  325. 
Disk-like  colony.     13,  Euglena  virulis,  Ehrb.  ;  one  of  the  Euglenina,  x  300  ;  «,  pigment  spot : 

b,  flagellar  reservoir;    c,  paramylum  granules;   <l,  chromatophores.      14,  Gonium  pectorale, 
O.  F.  M. ;  one  of  the  Volvocina  ;  colony  seen  from  the  flat  side,  x  300  ;  a,  nucleus  ;  b,  contractile 
vacuole  ;   c,  pyrenoid.     15,  Dinobryon  sertularia,  Ehrb.  ;  one  of  the  Chrysomonadina  loricata  : 

a,  nucleus  ;  b,  contractile  vacuole  ;  c,  paramylum,  (?)  nucleus  ;    d,  free  colourless  flagellates 
probably  not  belonging  to  Dinobryon, ;   e,  stigma ;  /,  chromatophores.     16,  Paranema  tricho- 
phorum,  Ehrb. ;  one  of  the  Paranemina,  x!40;  a,  nucleus  ;  6,  contractile  vacuoles  ;  c,  pharyn- 
geal  apparatus;  </,  mouth.      17,  anterior  end  of  Euglena  acus,  Ehrb.,  in  profile  ;   a,  mouth  : 

b,  contractile  vacuoles  ;   c,  pharynx  ;   d,  eye-spot ;  e,  paramylum  bodies  ;  /,  chromatophores. 
18,  part  of  the  surface  of   Volvox  globator,  L.,  showing  intercellular  connective  fibrils;    a, 
nucleus;  b,  contractile  vacuole;    c,  pyrenoid.     19,  two  antherozooids  (=  microgametes)  of 
Volvox  globator.    20,  ripe  asexually  produced  daughter  individual  of  Volvox  minor,  Stein,  still 
enclosed    in   the  cyst  of  the    parthenogonidium  ;   a,  young  parthenogonidia.      21  and  22, 
Undulina  ranarum,  E.  R.  L.  (see  Fig.  1,  p.  194).     23-26,  reproduction  of  Bodo  caudatus,  Duj. ; 
one  of  the  Heteromastigoda,  according  to  Dallinger  and  Drysdale.     23,  fusion  of  several  indi- 
viduals (plasmodium).     24,  encysted  fusion-product  dividing  into  four.     25,  later  into  eight. 
26,  cyst  filled  with  swarm-spores.     27,  Astasia  tenax,  O.  F.  M.  ;  one  of  the  Astasiina,  x  440. 
Individual  with  two  flagella  and  strongly  contracting  hinder  end  of  the  body  ;  o,  nucleus  ;  6, 
flagellar  reservoir.      28,  the  same  devoid  of  flagella.     20,  Oieomonas  termo,  Ehrb.  ;  one  of  the 
Protomastigina,   x  440 ;  «,  nucleus ;  b,  contractile  vacuole ;  c,   food-inge>ting  vacuole ;  d, 
food-particle.    30,  the  food-particle  has  now  been  ingested  by  the  vacuole.    31,  Oieomonas 
mutahilis,  Kent,  with  adherent  stalk  ;  «.,  nucleus  ;  6,  contractile  vacuole  ;  c,  food-particle  in  food- 
vacuole.     32,  33,    Cereobodo  (Cercomonas)  crassicauda,  Duj.,  showing  two  conditions  of    the 
pseudopodium  -  producing   tail ;   a,    nucleus ;    b,  contractile    vacuoles ;    e,    mouth.     (After 
Lankester  and  various  authors.) 

SUB-TRIBE  2.  PARAMASTIGODA.  Solitary  or  colonial  forms  with  one 
long  flagellum  and  one  (rarely  two)  short  accessory  flagellum  near  its 
base  ;  vacuolar  digestion  at  the  anterior  end.  A.  Solitary  genera. 
JV/onas,  Stein  ;  Sterromonas,  Kent ;  Physomonas,  Kent.  Freshwater. 
B.  Colonial  genera.  Cephalothamnium,  Stein  ;  Anthophysa,  Bory  (Fig. 
7  (12,  13)).  Freshwater. 

SUB-TRIBE  3.  HETEROMASTIGODA.  Solitary,  colonial,  free  or  attached 
forms  with  at  least  two  flagella  of  different  kinds,  of  which  one  is 
directed  forwards  and  another  is  directed  backwards,  acting  as  a 
gubernaculum  or  steering  flagellum  in  the  free  forms  or  as  a  stalk  of 
attachment  in  the  fixed  forms.  A.  Free  solitary  and  naked  genera  (Bodo- 
nina,  Biitschli)  ;  Bodo  (Fig.  7  (10)),  Ehrenberg — freshwater  and  marine  ; 


Pleuromonas,  Perty  ;  Phyllomitus,  Stein  ;  Colponema,  Stein  ;  Rhynchomonas, 
Klebs  ;  Oxyrrhis  (Fig.  10  (2)),  Duj. — marine.  Bodo  can  execute  character- 
istic jumping  movements  by  means  of  the  gubernaculum.  It  captures 
its  food  (bacteria  and  infusoria)  and  sucks  out  the  protoplasmic  contents 
by  means  of  a  rostral  process  (rostral  ingestion).  According  to  Dallinger 
and  Drysdale  a  process  of  plasmodium- formation  occurs  in  this  genii?, 
followed  by  encystment  and  subsequent  division  of  the  protoplasmic 
contents  into  numerous  swarm-spores  (Fig.  5  (23-26)).  In  Oxyrrhis  there 
is  a  large  oral  funnel  and  a  rudimentary  pharynx  similar  to  that  of  the 
Euglenoidea.  This  genus  is  said  to  divide  transversely  instead  of 
longitudinally  as  in  all  other  Heteromastigoda.  The  genus  Costia 
(Leclerq)  with  three  flagella,  reposing  in  a  groove  when  at  rest,  may 
belong  to  this  sub-tribe  (see  p.  157).  B.  Sedentary  and  usually  colonial 
forms,  protected  by  a  cup-shaped  or  closed  theca  and  attached  to  the 
base  of  it  by  the  gubernaculum.  At  the  anterior  extremity  there  is  a 
plate-like  expansion  of  the  ectoplasm  (the  peristome).  (Bikoecina,  Stein)  ; 
Bicosoeca,  Clark,  solitary  or  in  rosettes ;  (B.  socialis,  Lauterborn). 
Peristome  thin  and  membranous.  Freshwater  and  marine.  Poterio- 
dendron,  Stein,  fixed,  "  dinobryoid "  association  of  stalked  thecate 
individuals  ;  peristome  thick,  proboscis-like. 

The  Bikoecina  appear  to  suggest  a  transition  from  the  Lissoflagellata 
to  the  Choanoflagellata  in  virtue  of  their  peristome,  which  is  perhaps 
comparable  to  the  collar. 

The  Family  TRYPANOSOMATIDAE,  containing  the  blood-parasites  Try- 
panophis,  Trypanoplasma,  and  Trypanosoma,  belong  to  this  sub-tribe. 
The  family  is  fully  described  in  Section  G,  p.  193. 

SUB-TRIBE  4.  ISOMASTIGODA.  Monaxonic  body  with  two  equal 
flagella  at  the  anterior  end.  A.  Solitary  (Amphimonadina).  Amphimonas, 
Duj.  ;  Streptomonas,  Klebs  ;  Diplomita,  Kent.  Freshwater.  B.  Colonial 
(Spongomonadina).  Numerous  individuals  united  "in  a  common  jelly 
or  in  branched  gelatinous  tubes,  the  end  of  each  of  which  is  inhabited  by 
a  single  and  distinct  individual." l  Spongomonas,  Stein  ;  Cladomonas, 
Stein ;  Rhipidodendron,  Stein.  Diplomita  (Kent)  is  now  regarded  as  an 
individual  of  Spongomonas  living  isolated  in  the  theca  of  a  Bicosoeca.  All 

An  interesting  Protozoon  which  is  known  by  the  name  of 
Pseudospora  volvocis,  Cienkowski,  and  was  placed  by  Biitschli  in  the 
tribe  Isomastigoda,  is  found  parasitic  upon  Volwx.  According  to 
Robertson  (18),  it  has  three  forms,  each  from  12  to  30  /x  in  diameter. 
A,  an  amoeboid  form ;  B,  a  pear-shaped  flagellate  form,  with  two 
flagella  at  one  end  ;  C,  a  spherical  Actinophrys-like  form.  In  each  of 
these  forms  there  is  a  single  definite  nucleus  containing  a  centrally 
placed  karyosome  surrounded  by  clear  nucleoplasm.  The  amoeboid 
form  feeds  by  ingesting  individuals  of  the  Volwx  colony,  and  it 
gives  rise  to  the  flagellate  form,  which  swims  away  and  attacks 
another  colony.  Reproduction  of  the  amoeboid  form  occurs 

1  Lankester,  E.  R.,  Enci/.  Brit.,  9th  Ed.,  Art.  "Protozoa." 


accompanied  by  a  definite  mitotic  division  of  the  nucleus. 
Alternation  of  the  amoeboid  and  flagellate  forms  with  reproduction 
by  fission  continues  for  about  eighteen  days,  and  then  gameto- 
genesis  sets  in.  The  gametes  are  minute  (1-2  p,  in  length)  uni- 
fiagellate  organisms,  and  soon  after  their  escape  they  conjugate  in 
pairs  to  form  the  zygotes.  Gametogenesis  occurs  in  the  amoeboid 
form,  without  encystment  or  withdrawal  of  the  pseudopodia,  and  the 
number  of  gametes  formed  by  a  single  individual  may  exceed  one 
hundred.  After  a  time  the  zygotes  withdraw  their  flagella,  assume 
a  spherical  shape,  and  then  creep  into  a  Volwx  individual. 
Gametogenesis  may  also  occur  in  the  radial  form,  but  it  has  not 
been  observed  in  the  flagellate  form. 

It  does  not  seem  to  be  certain  that  the  species  described  belongs 
to  the  same  genus  as  others  that  have  been  attributed  to  Pseudospora 
(see  p.  8),  but  the  description  of  its  life-history  given  by  Miss 
Robertson  proves  that  it  is  not  a  Proteomyxan,  but  is  correctly 
placed  with  the  Mastigophora. 


With  more  than  two  flagella  (exclusive  of  Multicilia). 

SOB-TRIBE  1.  TRIMASTIGINA.  Three  flagella.  Trimastix,  Kent  ; 
Dallingeria,  Kent  ;  Elvirea,  Paroiia.  Costia  necatrix,  Henneguy,  is  a 
flagellate  ectoparasite  of  the  trout  which  cannot  live  in  infusions,  but 
requires  very  pure  water.  It  is  the  only  flagellate  ectoparasite  known 
which  cannot  live  apart  from  its  host.  It  penetrates  into  the  epidermis 
of  the  fry,  frequently  causing  a  mortal  disease.  The  adult  fishes  are 
immune,  being  protected  from  the  parasite  by  their  scales. 

SUB-TRIBE  2.  MoxosiOMATiNA.1  Four  (rarely  six)  flagella,  one 
mouth-spot  or  oral  groove,  unilateral,  asymmetrical.  Tetramitus,  Perty 
(Fig.  7  (14));  Collodictyon,C&i'teT;  Trichomonas,  Donne" ;  Trichomastix^loch- 
mann  ;  Monocercomonas,  Grassi  ;  Megastoma,  Grassi.  Megastoma  entericum, 
parasitic  in  man  and  domestic  animals,  is  regarded  as  intermediate 
between  the  Tetramitina  and  the  Distomatina  (Klebs),  having  a  uni- 
lateral mouth  as  in  Tetramitus  and  sextuple  flagella  as  in  Hexamitus. 
Trichomonas,  Donne.  T.  intestinalis  is  found  in  the  intestine  of  mice. 
"  It  is  pear-shaped  with  three  flagella  springing  from  the  blunt  end,  and 
an  undulating  membrane  with  a  thickened  border  passing  in  a  spiral 
manner  round  the  body  and  terminating  in  a  free  flagellum  "  (Wenyon). 

SOB-TRIBE  3.  DISTOMATINA,  Klebs,  1892.  Body  bilateral  but  not 
symmetrical,  since  the  two  mouth-spots  (oral  grooves)  are  placed  on 
opposite  surfaces  of  the  body  ;  flagella  arranged  in  pairs.  Principally 
found  in  stagnant  water.  Gyromonas,  Seligo,  4  flagella  ;  Trigonomonas, 
Klebs,  6  flagella  ;  Trepmnonas,  Duj.,  8  flagella  ;  Hexamitus,  Duj.  (Fig.  7 
(5)),  and  Urophagus,  Klebs,  with  6  or  8  flagella,  of  which  two  or  three 
pairs  are  anterior  and  the  fourth  pair  are  gubernacula  (Schleppgeisseln). 
The  two  last-named  genera  are,  alone  among  Flagellata,  characterised  by 

1  Including  the  Tetramitina,  with  a  wider  significance. 


forming,  as  products  of  metabolism,  glycogen-like  bodies  (Klebs).  H. 
muris  is  found  in  the  intestine  of  mice  (Wenyon).  Lamblia  intestinalis 
is  found  in  the  intestines  of  various  mammals,  and  is  not  infrequently 
parasitic  in  man.  It  is  not  thought  to  be  pathogenic.  Spironema,  Klebs. 
Polymastigote ;  flagella  arising  in  pairs  at  the  margins  of  the  spiral 

SDB-TRIBE  4.  LOPHOMONADINA,  exclusively  parasitic  in  the  rectum  of 
insects.  This  sub-tribe  is  regarded  by  some  authors  as  having  closer 
affinities  with  the  Ciliata.  It  has  already  been  described  under  the 
heading  Family  Trichonymphidae  in  Fasc.  II.  p.  417  of  this  Treatise. 
The  genus  Maupasia  (Schewiakoff)  has  the  anterior  part  of  the  body 
covered  with  cilia,  but  at  the  posterior  end  it  bears  a  long  flagellum.  By 
some  authors  it  is  regarded  as  a  Polymastigine  flagellate,  but  its  affinities 
seem  to  be  with  the  Ciliata.  Freshwater.  Hawaii.  Monomastix,  Roux,  is 
another  genus  with  a  polar  flagellum  and  cilia  in  longitudinal  rows. 
There  are  said  to  be  two  meganuclei  and  two  micronuclei.  This  genus 
should  also  be  included  in  the  Ciliata. 

ORDER  2.  Euglenoidea. 

The  second  order  of  Lissoflagellata  comprises  the  most  highly 
organised  members  of  the  sub-class.  This  high  degree  of  special- 
isation is  indicated  by  the  structure  of  the  pharyngeal  armature  of 
the  tribe  Peranemina,  which  consists  of  two  converging  rods,  which 
can  be  protruded  from  the  base  of  the  oral  funnel. 

With  regard  to  the  nutrition  of  Mastigophora  as  a  class,  to 
which  allusion  has  already  been  made,  it  is  necessary,  even  from  a 
purely  systematic  standpoint,  to  consider  (1)  the  nature  of  the 
food  ;  (2)  the  mechanism  of  ingestion ;  (3)  the  products  of  meta- 
bolism. In  holozoic  nutrition  the  food  consists  of  bacteria,  other 
monads,  swarm-spores  of  Algae,  starch,  and  the  like.  The  modes 
of  ingestion  by  which  these  food-bodies  are  conveyed  into  the  pro- 
toplast of  the  feeding  organism  are  of  five  principal  kinds,  namely, 
pseudopodial  ingestion  (Pantostomatina) ;  vacuolar  ingestion  (Mono- 
mastigoda,  Paramastigoda,  Isomastigoda,  Choanoflagellata) ;  rostral 
or  suctorial  ingestion  (Heteromastigoda) ;  stomatic  ingestion,  by 
which  the  food  sinks  into  the  protoplasm  through  one  (Monostoma- 
tina)  or  two  (Distomatina)  points  of  least  resistance  situated  in  one 
or  two  depressions  (oral  grooves)  below  the  insertion  of  the  flagella ; 
pharyngeal  ingestion  (Peranemina). 

Not  only  does  the  mode  of  feeding  distinguish  the  Peranemina 
from  all  other  Flagellata,  but  they  are  further  distinguished  by 
their  well-marked,  spirally  striated  periplast  or  cuticula.  In  the 
Euglenoidea  the  periplast  is  generally  a  striated,  resistent  proteid- 

The  vacuole-system  of  the  Euglenoidea  consists  of  a  non-con- 
tractile or  feebly  contractile  reservoir  provided  with  an  excurrent 


canal  opening  at  the  apex  of  the  cell,  and  one  or  many  accessory 
contractile  vacuoles  discharging  into  the  reservoir  (Fig.  5(17)).  A 
similar  kind  of  compound  vacuole-system  is  also  met  with  among 
the  Peridiniales  (Fig.  12). 

The  products  of  metabolism  which  occur  in  the  Euglenoidea 
consist  of  fatty  oil  and  paramylum,  a  substance  allied  to  starch,  but 
not  giving  the  typical  starch-reaction.  It  is  interesting  to  note  that 
the  saprophytic  Euglenoids  of  the  tribe  Astasiina,  which  are  destitute 
of  chlorophyll,  none  the  less  produce  paramylum. 

The  Euglenoidea  include  holozoic,  holophytic,  saprophytic,  and 
mixotrophic  species,  and  one  of  the  most  characteristic  properties 
which  they  have  in  common  is  the  formation  of  paramylum  as  the 
principal  product  of  metabolism. 

This  order  presents  a  series  of  forms  analogous  to  the  Mona- 
didea  in  regard  to  the  distribution  of  the  flagella  :  monomastigote 
forms  (JEuglena,  Peranema,  dstasin) ;  paramastigote  (Distigma, 
Sphenomonas,  Tropidoscyphus) ;  isomastigote  (Eutreptia) ;  and,  finally, 
heteromastigote  forms  (Heteronema,  Dinema,  Anisowma). 

The  Euglenoidea  are  divisible  into  two  sections  and  three  tribes. 

A.  Without  special  pharyngeal  apparatus. 


Holophytic.  A  red  stigma  or  eye-spot  close  to  the  vacuole  is  present, 
.iind  green  chromatophores. 

Euglena,  Ehrb.  (Fig.  5  (13,  17))  ;  Colacium,  Ehrb. ;  Lepocinclis,  Perty  ; 
Trachelomonas,  Ehrb.  ;  Eutreptia,  Perty ;  Ascoglena,  Stein ;  Cryptoglena, 
Ehrb.  Trachelomonas  is  sometimes  found  in  the  sea  ;  the  others  are 
freshwater  forms. 


Saprophytic,  without  chlorophyll.  Astasia  (Fig.  5  (27,  28)),  Duj.  ; 
Distigma,  Ehrb. ;  Sphenomonas,  Stein ;  Menoidium,  Perty ;  Rhabdomona.*, 
Fresenius  ;  Atractonema,  Stein.  All  freshwater  forms. 

B.  With  special  pharyngeal  apparatus. 



a.  With  one  flagelluin.  Paranema  (Fig.  5  (16)),  Duj.  ;  Euglenopsis, 
Klebs ;  Urceolus,  Meresch.  ;  Petalomonas,  Stein ;  Scytomonas,  Stein.  All 
found  in  fresh  water,  but  Euglenopsis  flourishes  in  vegetable  infusions. 
•Copromonas,  Dobell  (3),  parasitic  in  intestine  of  frogs. 

(3.  With  two  flagella.  Heteronema,  Duj. ;  freshwater  and  marine. 
Dinema,  Perty ;  stagnant  freshwater.  Zygoselrnis,  Duj. ;  freshwater.  Tropi- 
doscyphus,  Stein ;  freshwater;  Anisonema,  Duj.  ;  freshwater  Entosiphon, 
Duj.  ;  marine  and  freshwater. 


One  of  the  commonest  of  the  Euglenoidea  is  Euglena  viridis,  a 
species  which  is  frequently  found  in  shallow  ditches  and  puddles, 
giving  the  water  a  green  tint  or  forming  a  green  scum  on  its- 
surface.  The  free -swimming  individuals  are  about  O'l  mm.  in 
length,  provided  with  a  single  flagellum  arising  just  in  front  of  a 
short  funnel-shaped  cytostome  at  the  pointed  anterior  end  of  the 
body.  Opening  into  the  cytostome  funnel  there  is  a  small  reservoir, 
which  itself  receives  the  fluids  discharged  by  a  system  of  minute 
contractile  vacuoles.  The  chlorophyll  is  present  in  the  form  of 
numerous  minute  chloroplasts,  and  the  paramylum  in  the  form  of 
many  minute  plates.  At  the  base  of  the  flagellum  there  is  a  red 
eye -spot  composed  of  numerous  granules  of  "  haematochrome." 
There  is  a  single  nucleus.  An  important  phase  in  the  life-history 
is  the  resting  stage.  The  individuals  swarm  to  the  surface  of  the 
water,  where  they  form  the  green  scum.  Each  individual  in  the 
scum  loses  its  flagellum,  and,  secreting  a  gelatinous  substance 
which  joins  with  that  of  its  neighbour's  to  form  a  continuous  jelly,, 

Division  of  the  nucleus  and  cell-substance  takes  place  during 
the  resting  stage  at  night.  The  mi  to  tic  changes  commence  about 
two  hours  after  dark  and  are  completed  in  five  hours.  The 
nucleus  has  in  the  resting  stage  a  centrally  placed  "  nucleolo- 
centrosome."  This  becomes  dumb-bell-shaped  and  then  elongates- 
in  mitosis.  The  chromosomes  become  parallel  to  this  body,  and 
eventually  form  an  equatorial  ring  round  it.  In  this  position  they 
undergo  longitudinal  splitting  (Keuten). 

Euglena  undergoes  several  successive  divisions  under  the  same 
cyst-membrane,  forming  quadrants,  octants,  etc.,  but  all  result  from 
successive  longitudinal  division,  unlike  the  ciliate  infusorian  Colpoda,. 
which  produces  similar  clusters  resulting  from  successive  cross- 
division.  Again,  in  the  Volvocines  the  clusters  arise  by  alternate 
longitudinal  and  transverse  division  (Klebs). 

Thus,  in  the  case  of  Euglena  and  Copromonas,  division  takes- 
place  after  the  loss  or  withdrawal  of  the  flagellum,  but  in  the  allied 
Astasiina  division  takes  place  during  the  motile  phase. 

Euglena  gracilis  occurs  in  both  green  and  colourless  conditions, 
so  that,  employing  Pfeffer's  terminology,  it  may  be  at  one  time 
autotrophic  (holophytic),  at  another  time  heterotrophic  (sapro- 
phytic),  the  two  conditions  being  connected  by  a  mixotrophic 

An  important  contribution  to  the  life-history  of  the  Euglenoidea 
has  recently  been  made  by  Dobell  (3).  In  Copromonas  subtilis,  from 
the  intestine  of  the  common  frog  and  toad,  reproduction  is  effected 
by  simple  longitudinal  fission  accompanied  by  amitotic  division  of 
the  nucleus.  After  a  period  of  from  two  to  six  days  a  considerable 
number  of  individuals  are  found  to  be  conjugating.  All  the 


individuals  appear  to  be  facultative  gametes  and  there  is  no  sexual 
differentiation.  During  the  conjugation  the  nucleus  of  each  of  the 
conjugants  divides  at  least  once,  one  of  the  daughter  nuclei  thus 
produced,  being  a  polar  nucleus,  degenerates  in  the  cytoplasm  and 
is  lost.  The  remaining  nucleus  of  each  conjugant  fuses  with  its 
fellow  to  form  the  nucleus  of  the  zygote.  It  should  be  stated  that 
after  the  first  division  of  the  nuclei  of  the  conjugants  small  granules 
of  chromatin  are  protruded  from  the  central  chromatin  mass  and 
are  lost  in  the  cytoplasm  (heteropolar  division).  The  zygote 
behaves  exactly  like  an  ordinary  individual  and  divides  soon  after 
it  is  formed  by  longitudinal  fission  in  the  ordinary  manner. 

ORDER  3.  Chrcmomonadidea. 

This  is  the  first  of  the  groups  of  Mastigophora  that  are  regarded 
by  many  authors  as  belonging  to  the  vegetable  kingdom ;  for, 
although  there  is  an  active  free- swimming  stage  of  life,  the  method 
of  nutrition  appears  to  be  in  all  cases  holophytic.  In  the  Chloro- 
monadina,  which  may  be  regarded  as  in  many  respects  intermediate 
between  this  order  and  the  other  Lissoflagellata,  there  is  a  funnel- 
shaped  depression  at  the  base  of  the  flagellum ;  but  this  does  not 
serve  the  purposes  of  a  mouth,  but  is  an  excretory  duct  of  the 
contractile  vacuole  reservoir.  In  the  other  tribes  of  the  order 
even  this  vestige  of  the  Lissoflagellate  mouth  is  lost.  The  Chloro- 
monadina  also  resemble  the  Euglenoids  in  having  the  chlorophyll 
scattered  through  the  endoplasm  in  minute  chloroplasts.  No 
process  of  conjugation  has  yet  been  observed  in  this  order.  Among 
the  Chrysomonadina,  Chrysamoeba  has  the  ordinary  form  of  a 
flagellate  organism  when  it  is  actively  swimming,  but  when  it 
comes  to  rest  it  protrudes  delicate  radiating  pseudopodia  and 
resembles  a  Mastigamoeba. 

Chromulina  rosanoffi,  according  to  Woronin  (23),  forms  a  scum  of 
encysted  individuals  at  the  surface  of  ponds  in  Finland.  This 
gives  rise  to  the  flagellate  swarm-spores  which  after  a  time  penetrate 
the  cells  of  Spirogyra  and  again  encyst.  In  Dinobryon  the  indi- 
viduals are  attached  to  the  base  of  an  open  receptacle.  They 
usually  occur  in  dense  spreading  free-swimming  colonies  (Fig.  5  (8)). 
Reproduction  is  by  fission  or  by  the  formation  of  spherical  cysts 
which  escape  from  the  receptacle  and  start  new  Dinobryoid  colonies. 
Syncrypta  (Fig.  5  (4))  forms  globular  colonies  invested  by  a 
mucilaginous  test  through  which  the  flagella  protrude.  Uroglena 
also  forms  globular  colonies,  but  the  flagellate  individuals  are  at  the 
periphery  and  the  centre  is  filled  with  mucilage. 

The  genera  comprised  in  this  order  are  freshwater  in  habit, 
except  the  Coccolithophoridae,  which  are  exclusively  marine. 

The  order  is  divided  into  three  tribes  : — 



The  body  is  naked,  the  periplast  consisting  of  a  smooth  non-resistent 
membrane  formed  by  a  thick  layer  of  ectoplasm,  in  place  of  the  in- 
tegument of  the  Euglenoids.  The  chloroplasts  are  generally  numerous 
and  the  vacuole-system  is  compound,  resembling  that  of  the  Euglenoids. 
The  product  of  metabolism  is  neither  starch  nor  paramylum,  but  fatty 
oil.  There  is  a  funnel-shaped  depression  at  the  base  of  the  flagellum 
corresponding  with  the  cytostome,  but  not  used  for  the  ingestion  of  food. 

Genera — Facuolaria,  Cienkowski  ;  Coelomonas,  Stein;  Raphidomonas, 

TRIBE  2.   CHRYSOMONADINA,  Biitschli. 

The  members  of  this  tribe  resemble  the  Protoinastigina,  with  the 
addition  of  chromatophores  which  carry  a  yellowish-brown  pigment  called 
chrysochrome,  allied  to  diatomin.  The  chrysochrome-plates  are  usually 
two  in  number,  placed  right  and  left.  They  do  not  contain  pyrenoida 
and  do  not  manufacture  starch.  There  is  a  red  stigma  (eye-spot).  The 
products  of  metabolism  are  fatty  oil  and  a  refringent  soluble  proteid 
called  leucosin  (Klebs). 

Nutrition  is  generally  holophytic ;  there  is  no  mouth  ;  generally  two 

The  tribe  is  divided  by  Klebs  into  three  sections  or  sub-tribes  : — 


Chrysamoeba,  Klebs ;  Chromulina,  Cienkowski ;  Ochromonas,  Vyssotzki ; 
Stylochrysalis,  Stein.  The  last-named  is  attached  to  colonies  of  Eudorina. 


Dinobryon,  Ehrenberg  (Fig.  5  (8,  15))  ;  Hyalobryon,  Chi-ysopyxis,  Ehrb.; 
Chrysococcus,  Klebs  ;  Cyclonexis,  Senn. 

The  researches  of  Lohmann  (11)  have  shown  that  the  family 
Coccolithophoridae  must  be  included  in  this  group. 

The  members  of  this  family  are  extremely  minute  organisms, 
of  which  the  largest  species  are  only  25-50  p.  in  diameter,  found  in 
the  plankton  of  the  sea  and  characterised  by  the  possession  of 
a  theca  composed  of  minute  calcareous  shells  which  have  long 
been  familiar  to  zoologists  under  the  names  "coccoliths"  and 
"  rhabdoliths." 

The  organism  bears  one  flagellum  or  two  equal  flagella,  a  single 
nucleus,  two  (rarely  one)  large  green  or  brown  chromatophores, 
each  containing  a  drop  of  a  substance  which  appears  to  be  oil 
(Fig.  6,  D),  and  in  many  cases  a  vacuole  situated  near  the  base  of 
the  flagellum.  The  body  is  surrounded  by  a  soft  membrane  which 
supports  the  theca  of  calcareous  shells.  The  shape  of  the  shells 
that  compose  the  theca  shows  immense  variety  in  the  family.  Two 



kinds  have  been  distinguished,  those  that  are  imperforate  (discoliths, 
lopadoliths,  calyptroliths),  and  those  that  have  a  central  perforation 
(Fig.  6,  B)  (placoliths  and  rhabdoliths).  The  significance  of  the  per- 
foration in  the  placoliths  and  rhabdoliths  is  not  clear,  but  there  is 
no  evidence  at  present  that  it  transmits  protoplasmic  processes  from 
the  ectoplasm. 

When  the  theca  is  once  formed  it  is  never  increased  in  size  by 
the  addition  of  new  shells,  but  when  the  growth  of  the  organism 



FIG.  6. 

To  illustrate  the  structure  of  the  Coccolithophoridae.  A,  Scyphosphaera  apsteini,  Lohmann,. 
X  2000.  (j,  a  girdle  of  peculiar  enlarged  coccolitlis.  B,  optical  vertical  section  of  an  example 
of  a  perforated  coccolith  of  Coccolithrrpora  Irptopora,  M.  and  B.  C,  side-view  of  a  simple  collar- 
shaped  imperforate  coccolith  of  Calyptrosphaera  oblonga,  Lohmann.  D,  vertical  section  of 
Pontosphuera  haeckelii,  Loh.  ;  co,  the  sheath  of  coccolitlis  ;  ch,  the  two  chromatophores',  eacli 
containing  a  highly  refractive  globule  ;  /,  the  flagellum  ;  n,  the  nucleus.  B,  side-view  of  one 
of  the  coccolitlis  of  the  same  species.  F,  Discosphaera  tubifer,  M.  and  B.  ;  ch,  chromatophores. 
G,  trumpet -shaped  projection  from  the  coccolith  of  Discosphaera  tubifer,  x  2000.  '(After 
Lohmann  and  Murray  and  Blackman.) 

requires  it,  the  theca  is  cast  off  as  a  whole  and  a  new  one  formed 
in  its  place. 

Reproduction  is  usually  effected  by  simultaneous  longitudinal 
fission  of  the  theca  and  protoplasm,  but  occasionally  large  thecae 
are  found  containing  two  individuals,  indicating  that  fission  of  the 
protoplasm  may  precede  division  of  the  theca  or  the  formation  of 
two  thecae. 

No  evidence  has  yet  been  obtained  of  the  formation  of  gametes. 

The  Coccolithophoridae  are  exclusively  marine,  but  are  found 
everywhere  except  in  pure  polar  waters.  They  reach  their  greatest 
numbers  at  a  few  fathoms  from  the  surface. 


Sub-Family  SYRACOSPHAERINAE.  Pontosphaera  (Fig.  6,  D),  Scypho- 
sphaera  (Fig.  6,  A),  Syracosphaera,  and  Calyptrosphaera — all  described  by 

Sub-Family  COCCOLITHOPHORINAE,  Lohmann.  Coccolithopora,  Loh. ; 
Umbilicosphaera,  Loh.  ;  Discosphaera,  Haeck.  (Fig.  6,  F) ;  Rhabdosphaera, 


Mallomonas,  Perty  ;  Synura,  Ehrenberg ;  Syncrypta,  Ehrenberg  (Fig. 
5  (4))  ;  Uroglena,  Ehrenberg  (Fig.  5  (5)) ;  Microglena,  Ehrenberg ;  Hymeno- 
monas,  Stein. 


Coloured  or  colourless  forms  with  one  to  three  green  chromatophores 
or  none.  Nutrition  is  never  holozoic  and  the  product  of  metabolism  is 
starch,  as  in  green  Algae  and  in  Dinoflagellata.  The  anterior  end  is 
more  or  less  obliquely  truncate,  usually  with  a  deep  frontal  infundibulum  l 
like  a  peristome,  from  the  side  or  bottom  of  which  the  two  flagella  arise. 

Cryptomonas  (holophytic),  Ehrenberg  ;  Cyathomonas,  Fromentel ;  and 
Chilomonas  (saprophytic),  Ehrenberg. 

In  Cryptomonas  the  colour  of  the  chromatophores  varies  from  green  to 
brown  and  yellow  ;  two  are  dorsal  and  one  ventral.  Cyathomonas  possesses 
no  chloroplasts. 

Closely  related  to  the  Cryptomonadina  are  the  Phaeocapsaceae,  contain- 
ing the  genera  Phaeococcus,  Borzi  ;  Phaeosphaera,  West ;  and  Stichogloea, 
Chodat.  In  these  forms  a  large  number  of  non-flagellate  cells  form  a 
mucilaginous  investment ;  but  as  the  asexual  reproduction  takes  place 
principally  during  this  phase  of  life,  they  are  more  usually  regarded  as 
algae.  The  same  may  be  said  of  the  genus  Hydrurus,  Ag.,  in  which  the 
cells  are  enclosed  in  a  tough  cylindrical  mucilaginous  envelope. 


The  Choanoflagellata  are  frequently  regarded  as  constituting 
a  subdivision  of  the  Protomastigina,  a  proceeding  which  is  in 
accordance  with  their  affinities,  though  such  is  the  singularity 
of  their  form  that  it  seems  quite  as  appropriate  to  preserve  their 
independence  as  to  merge  them  into  a  larger  group.  There  are 
no  permanently  free-swimming  species,  all  are  either  sessile  or 
pedunculate,  solitary  or  colonial.  They  can,  however,  quit  their 
.attachment  temporarily  and  swim  about  with  the  collar  directed 
backwards.  The  collar  may  be  defined  as  a  special  development 
of  the  peristome  surrounding  the  single  flagellum  which  acts  as  a 
pulsellum  in  locomotion.  The  collar  is  a  contractile  protoplasmic 
process  comparable  in  some  respects  to  an  undulating  membrane. 

The  organism  feeds  by  means  of  vacuolar  ingestion,  the  food 

1  Flagellar  fundus.     See  also  under  Dinoflagellata,  p.  187. 


particles  being  carried  down  on  the  outer  surface  of  the  collar,  at 
the  base  of  which  they  sink  into  the  body  of  the  cell. 

Several  of  the  genera  are  found  both  in  the  sea  and  in  fresh 

There  are  two  orders  of  Choanoflagellata  : — 

ORDER  1.  Craspedomonadina,  Stein. 
A.  NUDA,  Lankester. 

Monosiga,  Kent ;  Diplosiga,  Frenzel  (with  two  collars,  one  within  the 
other)  ;  Hirmidium,  Perty  ;  Codosiga,  Kent  (Fig.  7  (3,  4)). 

B.  LORICATA,  Lankester. 

Salpingoeca,  Clark  (Fig.  7  (1,  6,  7));  Polyoeca,  Kent;  Sphaeroeca, 

ORDER  2.  Phalansteriina  (  =  Gelatinigera,  Lankester). 

"The  cell-units  secrete  a  copious  gelatinous  investment  and  form 
large  colonies." 

Phalansterium,  Cienkowski  (Fig.  5  (12)),  with  inconspicuous  collars  ; 
Proterospongia,  Kent  (Fig.  7  (15)),  with  conspicuous  collars. 


The  Phytoflagellata  or  Volvocaceae  are  clearly  related  to  the 
Chromomonadidea,  and  some  authors  include  this  order  in  the  sub- 
class. Now  that  it  has  been  definitely  ascertained  that  conjugation 
does  occur  in  many  of  the  Euflagellata,  the  formation  of  a  zygote  by 
the  copulation  of  two  gametes  is  a  feature  that  does  not  distinguish 
the  Phytoflagellata  from  the  other  sub-classes  of  the  Mastigophora. 
Moreover,  although  in  Copromonas  and  some  other  Monadidea  the 
conjugating  individuals  cannot  be  distinguished  from  the  asexual 
individuals,  definite  micro-  and  megagametes  are  formed  in  the  life- 
history  of  Mastigella,  Trypanosoma,  and  others.  The  phenomenon  of 
gametogenesis  therefore  is  not  a  distinguishing  character  of  the 
sub-class.  The  Phytoflagellata,  however,  exhibit  a  much  more 
definite  approximation  to  a  purely  vegetable  structure  than  any 
of  the  Euflagellata,  and  it  may  be  convenient  to  keep  them  together 
for  the  present  in  a  separate  sub-class. 

The  sub-class  includes  solitary  and  colonial  forms,  and  the  body 
of  the  cell-unit  is  enclosed  by  a  firm  cell-wall  which  sometimes  takes 
the  form  of  a  bivalvate  shell  (Phacolus).  In  the  colonial  forms  the 
cell -units  are  embedded  in  a  gelatinous  matrix.  There  is  no 
indication  of  pharynx,  nutrition  being  holophytic  except  in  the  case 
of  Polytoma,  which  is  a  colourless,  saprophytic  Chlamydomonad. 


There  is  usually  a  single  large  green  chloroplast  enclosing  one 
or  more  pyrenoids,  and  the  product  of  metabolism  is  starch.  The 
vacuole-system  consists,  as  a  general  rule,  of  two  alternately  con- 
tracting vacuoles.  There  is  a  red  stigma  at  or  near  the  flagellar 
basis.  There  are  never  less  than  two  equal  flagella,  rarely  four  as 
in  Carteria  and  Pyramidomonas. 

The  Phytoflagellata  are  freslnvater  in  habit. 

Among  the  organisms  which  are  closely  related  to  the  Phytoflagellata, 
but  which  are  regarded  in  this  volume  as  being  just  over  the  border-line 
between  the  animal  and  vegetable  kingdoms,  we  may  include  the  families 
Pleurococcaceae,  Hydrodictyaceae,  Protococcaceae,  and  Palmellaceae.  The 
genera  Pleurococcus,  Menegh.,  and  Trochiscia,  Kiitzing,  belonging  to  the 
Pleurococcaceae,  have  a  more  definite  cell -wall  and  a  more  pronounced 

FIG.  7. 

1,  Scdpingoeea  fusiformis,  Kent;  one  of  the  Craspedomonadina.  The  protoplasmic  body  is 
drawn  together  within  the  goblet-shaped  cell,  and  divided  into  numerous  spores,  x  1500. 
2,  escape  of  the  spores  of  the  same  as  monomastigote  swarm-spores.  3,  Codosigc  vmlieUntii, 
Tatem  ;  one  of  the  Craspedomonadina.  Adult  colony  formed  by  dichotomous  growth,  x  625. 

4,  a  single  zooid  of  the  same,  x  1250.    a,  nucleus;  b,  contractile  vacuole ;  c,  the  collar. 

5,  Hexam  itux  i/ijlutus,  Duj.  ;  one  of  the  Polymastigina,  x  650.    Normal  adult  showing  (».)  nucleus 
and  (6)  contractile  vacuole.    6,  7,  Salpingoeca  ttrceolata,  Kent;  one  of  the  Craspedomonadina. 
('>,  with  collar  extended  ;  7,  with  collar  retracted  within  the  stalked  cupule.     8,  Polytoma  urvlln, 
Miill.  ;  one  of  the  Chlamydomonadina,  x  800  ;  «,  nucleus  ;  1),  contractile  vacuoles.    P,  Lopfcomowu 
Mathirum,  Stein  ;  one  of  the  Polymastigina.    10,  Bodo  lens  ;  one  of  the  Heteromastigoda,  x  800  ; 
K,  nucleus;  b,  contractile  vacuole;  the  wavy  filament  is  a  flagellum,  the  straight  one  is  the 
gubernaculum.     11,  TetrutiiifH*  .--iili'ittits,  Duj.;  one  of  the  Polymastigiiia,  x  430;  a,  nucleus; 
ft,  contractile  vacuoles.     12,  Anthophysu  rryetans,  O.  F.  M.  ;  one  of  the  Paramastigoda,  x  300. 
A  typical,  erect,  shortly-branching  colony  stock  with  four  terminal  monad  clusters.    13,  monad 
fluster  in  same  optical"  section  (x  800),  showing  the  relation  of  the  individual  monads  to  the 
stem  (a).    14,  Tetrniiutun  /•«.-•/;•,  itn.t.  Ferty,  x  1000 ;  a,  nucleus;   b,  contractile  vacuole.     15, 
Proterospongia  haeckeli,  Kent ;  one  of  the  Phalansteriina,  x  800.    A  social  colony  of  about  forty 
flagellate  zooids.    o,  nucleus ;  b,  contractile  vacuole ;  c,  amoebiform  zooid  sunk  within  the 
common  test ;  c/,  similar  zooid  multiplying  by  transverse  fission  ;  e,  normal  zooids  with  their 
collars  retracted  ;  /,  hyaline  mucilaginous  common  test  or  zoothecium  ;  g,  individual  contracted 
and  dividing  into  minute  flagellate  spores  (microgametes),  comparable  to  the  spermatozoa  of  a 
sponge.     (After  Lankester  and  various  authors.) 

vegetative  phase  of  life  than  SpJuierella,  but  in  other  respects  are  closely 
related  to  it.  The  genus  Hydrodictyon,  Roth,  forms  a  net-like  coenobium 
which  floats  at  the  surface  of  the  water,  and  Fediastrum,  Meyen,  which 
is  also  placed  in  the  family  Hydrodictyaceae,  a  flat  plate-like  coenobium 
of  cells  that  is  protected  by  a  thick  and  ornamented  cell-wall.  Among 
the  Protococcaceae  such  genera  as  Botryococcus,  Kiitzing  ;  Tetracoccus, 
West ;  Ineffigiata,  West,  are  probably  closely  related  to  some  ancestral 
form  allied  to  tiphaerella  ;  but  in  some  of  the  other  genera,  such  as 
Selenastrum,  Reinsch  ;  Ankistrodesmus,  Corda  ;  Dadylococcus,  Nageli,  in 
which  the  cells  are  elongated  and  spindle-shaped  ;  and  in  Archerina, 
Lankester 1  ;  and  Chodatella,  Lemmermann,  in  which  the  cell-walls  are 
provided  with  long,  stiff,  bristle-like  processes,  there  is  a  more  pronounced 
diversion  from  the  Chlamydomonadine  ancestry. 

The  family  Palmellaceae  has  diverged  from  the  same  ancestry  by  the 
development  of  a  conspicuous  envelope  of  mucilage,  but  it  contains  some 

1  The  genera  Golenklnin,  Chodat,  Richteriella,  Lemmermann,  and  Phytiielivs, 

Frenzel,  are  probably  the  same  as  Archerina  (see  p.  33). 


of  the  most  primitive  of  the  Chlorophyceous  Algae.  The  principal  genera 
are  Palmella,  Lyngbye  ;  Palmodactylon,  Nageli  ;  Sphaerocystis,  Chodat ; 
Schizochlamys,  A.  Br.  ;  Tetraspora,  Link ;  Apiocystis,  Nageli  ;  Gloeocystu, 
Nageli ;  and  Palmodictyon,  Kiitzing. 

ORDER  1.  Chlamydomonadina. 

Solitary  forms  in  the  flagellate  phase. 

In  Chlamydomonas,  which  may  be  taken  as  an  example  of  this 
order,  there  are  two  flagella  in  the  free-swimming  stage,  the  body 
is  enclosed  in  a  cellulose  investment,  there  are  two  small  contractile 
vacuoles  at  the  anterior  end,  a  stigma  (eye-spot),  a  single  nucleus, 
and  one  or  more  pyrenoids.  Two  individuals  may  conjugate  and 
form  a  zygote.  The  zygote  encysts,  the  flagella  being  lost,  and 
the  protoplasmic  contents  divide  into  as  many  as  sixty-four  cells 
(Fig.  5  (3)) ;  these  cells  escape  as  flagellate  individuals  similar  in 
general  characters  to  the  gametes,  but  instead  of  conjugating  they 
form  a  gelatinous  investment,  lose  their  flagella,  and  divide  repeatedly 
(the  "  palmella- stage  ").  From  the  gelatinous  investment  of  the 
colony  that  is  thus  formed  the  flagellate  gametes  ultimately  escape. 
Reproduction  may  also  occur  by  the  formation  of  a  resting  cyst  and 
the  division  of  the  cell-contents  into  two,  four  (Fig.  5  (2)),  or  eight 
cells,  which  escape  in  a  form  like  the  parent. 

The  introduction  into  the  life-history  of  this  genus  of  a  non- 
flagellate  "  palmella-stage  "  during  which  growth  and  reproduction 
take  place  has  suggested  that  Chlamydomonas  "is  the  phylogenetic 
starting-point  of  the  various  lines  of  Chlorophyceous  descent" 
(Blackman  and  Tansley).  That  there  is  a  strong  resemblance 
between  the  swarm-spores  of  many  Algae  and  flagellate  forms  such 
as  Chlamydomonas  cannot  be  denied,  but  the  conclusion  that  all  the 
green  Algae  are  descended  from  a  flagellate  ancestry  is  not  universally 
accepted  (see  West  [22],  p.  33). 

Sphaerella,  Sommerfeldt,  1824,  is  probably  the  correct  generic  name 
for  a  very  abundant  organism  found  in  rain-pools,  water-butts,  etc.,  that 
is  sometimes  called  Haematococcus,  Agardh  ;  Chlamydococcus,  Braun  ;  or 
Protococcus,  Huxley  and  Martin.  The  individuals  may  become  brick-red 
owing  to  the  presence  of  "  Haematochromin,"  and  give  rise  to  the 
phenomena  known  as  "red  rain"  and  "red  snow."  The  structure  and 
life-history  of  this  organism  are  very  similar  to  that  of  Chlamydomonas. 
The  infecting  organism  which  forms  the  green  cells  in  the  Turbellariait 
worm  Convoluta  roscoffensis  is,  according  to  Keeble  and  Gamble  (7),  a 
Chlamydomonad  allied  to  Carteria. 

The  principal  genera  are  : 

Carteria,  Diesing,  with  four  flagella ;  Chlamydomonas,  Ehrenberg  ; 
Sphaerella,  Sommerfeldt  (Fig.  5  (9, 10)) ;  Haematococcus,  Agardh  ;  Polytoma, 
Ehrenberg  (Fig.  7  (8)) ;  Chlorogonium,  Ehrenberg  (Fig.  5  (6)) ;  Pyramimonas, 


ORDER  2.  Volvocina. 

Individuals  biflagellate,  arranged  in  colonies  called  "coenobia," 
of  definite  forms,  with  a  gelatinous  matrix.  Reproduction  takes 
place  by  the  cleavage  of  certain  individuals  (cells)  of  the  colony 
called  the  gonidia.  There  are  two  kinds  of  gonidia — the  partheno- 
gonidia  or  asexual  forms,  and  the  gametogonidia  or  sexual  forms. 
The  gametogonidia  consist  of  the  oogonidia  or  female  gametes  and 
the  antherogonidia  or  spermatozooids.  These  conjugate  to  form 
the  zygotes. 

The  volvocine  colony  is  physiologically  an  individual  organism, 
exhibiting  histological  differentiation  and  correlated  locomotor 
Activities  of  the  constituent  cells.  In  Eudorina  the  cells  are 
differentiated  into  male  and  female,  the  male  cells  arising  from  the 
anterior  quartet,  the  remainder  becoming  female.  In  Volvox  the 
reproductive  cells,  both  parthenogonidia  and  gametogonidia,  arc 
limited  to  a  few  of  the  cells  which  compose  the  coenobium.  In 
Pleodorina  the  parthenogonidia  are  confined  to  the  posterior 
hemisphere  (Fig.  9). 

Protoplasmic  intercellular  connections  between  the  cells  (in- 
dividuals composing  the  colony)  only  occur  in  the  genus  Volwx, 
in  apparent  correlation  with  the  high  degree  of  individuation 
attained  by  this  form.  Each  cell  or  "  coenocyte "  is  contained 
within  its  own  capsule,  which  is  separated  from  neighbouring 
capsules  by  a  radial  cell-wall.  The  sarcode  is  separated  from  the 
cell-walls  by  a  wide  space  which  is  occupied  by  the  gelatinous 
matrix,  and  protoplasmic  processes  radiate  through  the  matrix  and 
traverse  the  cell-walls  (Fig.  5  (18)). 

The  coenobium  of  Volvox  is  a  sphere  consisting  of  a  single  layer 
of  cells  surrounding  a  central  cavity,  and  thus  presents  a  superficial 
analogy  to  the  blastula- stage  in  the  embryonic  development  of 
Metazoa.  The  presence  of  flagella,  eye- spots,  and  contractile 
vacuoles  attest  its  animal  properties,  while  the  presence  of 
chromatophores,  pyrenoids,  and  starch  granules  proclaim  its 
vegetable  affinities. 

The  sphere  comprises  two  differently  constituted  hemispheres. 
The  trophic  hemisphere  is  that  Avhich  is  directed  forwards  during 
locomotion,  and  the  component  cells  are  distinguished  by  the 
brighter  development  of  the  eye-spots.  The  other  hemisphere  is 
the  generative  hemisphere,  in  which  the  oogonidia,  antherogonidia, 
and  parthenogonidia  are  chiefly  formed. 

Locomotion  is  rotatory,  i.e.  forward  progression  accompanied  by 
rotation  about  the  main  axis  either  to  the  right  or  to  the  left, 
though  sinistral  rotation  is  more  frequent  than  dextral. 

In  Volvox  globator,  L.,  the  average  number  of  cells  in  a  mature 
coenobium  is  10,000,  the  actual  numbers  ranging  from  a  minimum 



of  1500  to  a  maximum  of  22,000.  In  /'.  aureus,  Ehrb.,  the  number 
of  cells  varies  from  200  to  4400.  In  a  third  species.  V.  tertius, 
Meyer,  intercellular  protoplasmic  threads  are  only  present  in  young 
unhatched  colonies,  not  in  the  adult  condition. 

The  form  of  the  coenobium  varies  in  the  different  genera. 
Gonium,  Miiller  (Fig.  5  (14))  ;  cells  4-16,  arranged  in  a  squarish  plate 
with  flagella  upon  one  face  only  ;  envelope  closely  adherent.  Stephano- 
fphaera,  Cohn  ;  cells  4-8,  arranged  in  a  rounded  plate  with  flagella  upon 
one  face  only  ;  envelope  swollen  ;  oval  or  spherical.  Eudorina,  Ehrb.  ; 
coenobium  ellipsoidal  or  spherical  ;  cells  16-64,  similar,  not  crowded  nor 
reaching  towards  centre.  Pandorina,  Bory ;  coenobium  ellipsoidal  or 

spherical  ;  cells  16-32,  simi- 
lar, crowded,  reaching  to- 
wards centre  ;  outer  mem- 
brane or  sheath  of  coero- 
biuni  showing  characteris- 
tic concentric  stratification. 
Platydorina,  Kofoid  (Fig. 
8) ;  coenobium  horseshoe- 
shaped,  flat,  one  cell  deep, 
with  3-5  prolongations  of  the 
gelatinous  matrix  at  the  pos- 
FIG.  8.  terior  end  ;  cells  16  or  32  ; 

Platydoniw.  w.mlata,  Kofoid.     A  plate-like  Volvocine  flagella    upon    both     sides     of 

colony.      The   two  surfaces   of  the  colony  are  alike.  .-,  •,    .         .,  ,,       nlfpr. 

The  aspect  of  the  adjacent  cells  alternates,  so  that  l 

the  pole  bearing  the  flagella  and  stignia  of  one  'cell  natin".        In     side    view    the 

is  turned  in  the  opposite  direction  to  that  of  its  im-  ,        °.  ,  , 

mediate  neighbours,  B,  x.    A,  front  view  of  the  colony  ;  plate    IS   seen    to     be    twisted 

B,  side  view;   C,  a  single  cell  showing, /,  the  flagella;  cliahtlv  in  a  Ipft    sniral    «r>  at 

T,  the  vacnoles  \  *t,  the  stignia  ;  N,  the  nucleus  ;  and  sllgntly  !1 

P,  the  pyrenoid.    (After  Kofoid.)  to     describe    a    figure    of    8. 

The  asexual  reproduction  of 

Platydorina  has  been  observed  by  its  discoverer  (Kofoid,  1900)  repeatedly 
during  five  years,  but  sexual  reproduction  has  not  been  seen  in  this  genus. 
All  the  cells  are  gonidial,  each  capable  of  dividing  to  form  a  daughter 
coenobium.  The  daughter  colonies  acquire  the  adult  form  and  torsion 
before  escaping  from  the  maternal  matrix,  which  then  undergoes  dis- 
integration. Pleodorina,  Shaw  (Fig.  9)  ;  coenobium  ellipsoidal  ;  cells  32, 
arranged  in  5  circles,  4  in  each  polar  circle,  8  at  the  equator,  and  8 
in  each  intervening  tract.  Vegetative  cells  always  4  at  the  anterior 
pole.  Gonidial  cells  twice  as  large  as  the  vegetative. 


The  Dinoflagellata  or  Peridiniales,  formerly  called  Cilioflagellata 
under  an  erroneous  impression  concerning  the  nature  of  the  trans- 
verse flagellum,  are  heteromastigote  forms  usually  possessing  a 
complete  cellulose  membrane  or  cuirass  which  is  never  silicified. 
The  chromatophores  are  predominantly  brownish  coloured  with  a 



pigment  known  as  peridinin.  Eeproduction  takes  place  by  oblique 
fission  (Fig.  11)  and  by  swarm-spores.1  There  are  two  flagella 
generally  lodged  in  grooves,  of  which  one  traverses  the  latitude  of 
the  body  and  the  other  the  longitude.  The  former  is  called  the 
annulus  or  girdle  and  the  transverse  flagellum  plies  within  it 
(Fig.  10  (3)).  The  longitudinal  groove  is  the  sulcus  harbouring  the 
longitudinal  flagellum. 

As  already  indicated,  the  Dinoflagellata  constitute  a  very 
important  component  of  the  freshwater  and  marine  plankton,  the 
same  generic  forms  occurring  in  both  media.  Moreover,  they  play 
an  important  part  in  the  physiology  of  oceanic  life  as  a  whole. 

FIG.  9. 

Pleoilorina  illinoisensis,  Kofoid.  Colony  of  thirty-two  cells.  The  four  small  cells  at  the 
.interior  pole  are  the  vegetative  cells  (w),  the  remainder  are  facultative  parthenogonidia, 
pp.  x  300.  (After  Kofoid.) 


There  is  no  cuirass,  but  the  grooves  are  present.  The  transverse 
groove  may  be  semiannular  in  extent  and  subcentral  in  position,  with  the 
longitudinal  fissure  straight  and  nearly  at  right  angles  to  it  on  the  ventral 
side  (Hemidinium,  Fig.  10  (1))  ;  or  the  transverse  groove  may  form  a  com- 
plete ring  subterminal  in  position  passing  into  the  ventral  longitudinal 
fissure,  the  anterior  or  prae-annular  portion  being  much  smaller  than  the 
posterior  and  presenting  the  appearance  of  a  rostrum  (Amphidinium) ;  again, 
the  annulus  may  be  complete  and  occupy  approximately  the  equator  of  the 
cell,  and  the  sulcus  straight  (Gymnodinium)  ;  finally,  both  annulus  and 
sulcus  may  have  a  spiral  twist  (Spirodinium,  etc.). 

1  Zederbauer  (24)  has  described  a  process  of  the  fusion  of  the  protoplasm  of  two 
individuals  of  Ceratiitm  hirundinella  which  he  regards  as  conjugation,  but  as  the 
further  history  of  the  zygote  (?)  has  not  been  traced,  it  may  be  only  of  the  nature  of 
plastogamic  union  such  as  we  find  in  the  Lobosa  and  Heliozoa. 

1 84 


The  genera  thus  fall  into  two  groups  : — 

A.  Annulus  and  sulcus  simple,  at  right  angles  to  one  another,  decus- 
sating at  one  point,  from  which  the  two  flagella  take  their  origin. 

Gymnodinium,  Stein.  Freshwater  and  marine.  Hemidinium,  Stein 
(Fig.  10  (1)).  Freshwater.  Amphidinium,  Clap,  and  Lach. 

FIO.  10. 

1,  Diagram  of  Hemidinium,  one  of  the  Dinoflagellata;  71,  nucleus;  /,  flagellum  of  the 
transverse  groove  ;  h,  flagellum  of  the  vertical  groove.  2,  diagram  of  Oxyrrhis,  one  of  the 
Heteromastigoda  (to  compare  with  the  preceding);  n,  nucleus;  g,  the  deep  fossa  or  pit  in 
which  the  two  flagella  are  affixed  ;  t,  the  origin  of  the  flagellum,  which  corresponds  with  that  of 
transverse  groove  of  Dinoflagellata.  3,  Glenodinium  einctum,  Ehrb.,  one  of  the  Peridiniaceae  ; 
a,  amyloid  granules ;  6,  eye-spot ;  c,  chromatophores ;  d,  flagellum  of  the  transverse  groove  ; 
«,  flagellum  of  the  vertical  groove ;  v,  vacuole.  4,  the  same  seen  from  the  hinder  pole.  5, 
cuticle  of  Histioneis  cymbalaria,  iStein,  from  the  Atlantic ;  i,  ventral  process  ;  k,  cuticular 
collar ;  I,  posterior  process.  6,  the  same  seen  from  the  dorsal  surface ;  m,  cephalic  funnel 
(epitheca).  7,  cuticle  of  Amphisolenin  globifera,  Stein,  from  the  Atlantic,  seen  from  the  left 
side  ;  m,  epitheca  ;  o,  the  fundus  from  which  the  sulcus  proceeds  to  the  sub-terminal  annulus  ; 
p,  pharynx ;  q,  the  shrunken  protoplasm.  8,  cuticle  of  Ornithocereus  magnificus,  Stein,  from 
the  Atlantic ;  m,  m',  the  epitheca  ;  r,  r',  the  two  large  ribs  of  the  cuticular  collar ;  s,  the  two 
rows  of  cuticular  teeth.  9,  cuticle  of  Ceratocorys  horrida,  Stein,  from  the  Southern  Ocean  ; 
p,  p',  borders  of  the  annulus  expanded  into  a  rim  ;  w,  x,  y,  plumose  spines  of  the  left  margin 
of  the  sulcus.  (After  Lankester  and  various  authors.) 


B.  Annulus  spiral  with  a  single  pitch,  sulcus  slightly  (Spirodinium) 
or  markedly  (Pouchetia)  spiral,  decussating  the  annulus  at  both  ends. 
The  transverse  flagellum  arises  at  the  anterior  end  of  the  annular  spire, 
the  longitudinal  flagellum  at  the  posterior  end  of  the  sulcar  spire. 

Spirodinium,  Schutt ;  Cochlodinium,  Schutt ;  Pouchetia,  Schu'tt.  All 

Pouchetia  resembles  Cochlodiniunt,  but  is  distinguished  by  the 
possession  of  a  complicated  stigmatic  apparatus  consisting  of  a  red  or 
black  pigmented  body  with  one  or  more  large  refractive  lens-like 
spherules  adjoining  it. 

The  interesting  genus  Polykrikos,  Btitschli,  consists  of  two,  four,  or 
rarely  eight  individuals  united  together  into  a  colonial  organisation 
(Kofoid  [10a]).  It  is  also  peculiar  in  the  possession  of  nettling  organs, 
and  is  said  to  present  holozoic  nutrition.  Coasts  of  Europe  and  California. 

All  Gymnodiniaceae  may  be  naked  or  enclosed  temporarily  in  a 
gelatinous  membrane.  The  tribe  includes  marine  and  freshwater  species. 


Carapace  bivalve,  perforated  with  numerous  pores,  without  annular 
plates  and  without  annulus,  the  two  halves  meeting  directly  like  the 
edges  of  two  opposed  watch-glasses;  longitudinal  flagellum  has  the 
•character  of  a  tractellum  with  the  transverse  flagellum  vibrating  about 
its  base  ;  chromatophores  yellow ;  contractile  vacuoles  represented  by 
pusulae  opening  into  the  groove  from  which  the  flagella  arise  at  the 
^interior  end  of  the  cell-body. 

At  the  time  of  division  each  daughter-cell  receives  one  parent  valve 
and  forms  the  other  anew.  The  Prorocentraceae  are  entirely  marine. 

Lotsy  (12)  regards  this  tribe  as  being  probably  similar  in  some  respects 
to  the  ancestors  of  the  Diatomaceae. 

Exuviaella,  Cienkowski,  rounded  in  front  and  behind.  Prorocentrum, 
Ehrenberg,  heart-shaped,  flattened,  pointed  behind,  with  rostral  prolonga- 
tion of  one  of  the  valves  at  the  anterior  or  flagellar  end. 


These  are  characterised  by  the  possession  of  a  multitabulate  cellulose 
.carapace  or  cuirass,  each  valve  being  composed  of  at  least  two  plates 
which  are  frequently  areolated,  and,  in  addition,  there  are  three  or  more 
mmular  and  sulcar  plates.  The  longitudinal  flagellum  plies  in  the 
sulcus ;  the  transverse  flagellum  arises  at  the  junction  of  sulcus  and 
annulus  and  vibrates  in  the  latter  groove  (Fig.  12). 

The  cellulose  membrane  which  constitutes  the  carapace  or  cell-wall 
•of  the  Peridiniaceae  is  perforated  by  minute  pores  and  is  generally 
provided  with  processes  which  may  take  the  form  of  horns,  spines,  or 
aliform  expansions. 

Multiplication  takes  place  by  oblique  longitudinal  (rarely  transverse) 
division,  each  daughter-cell  receiving  half  of  the  parent  carapace,  that  is 
to  say,  half  of  each  valve,  and  regenerating  the  other  half.  Resting 
:sporocysts  are  enclosed  in  a  gelatinous  membrane,  and  it  may  be  noted 

1 86 


that  the  endogenous  formation  of  swarm-spores  results  in  the  production 
of  gymnodiniform  young. 

Chromatophores,  indefinite  in  number,  may  be  green,  reddish  yellow, 
or  absent.  The  reddish-yellow  variety  of  chlorophyll  has  been  named 
peridiniu  (Schiitt).  The  colour  of  the  chromatophores  turns  green  at 
death  owing  to  the  solubility  of  the  peridinin.  Many  genera  comprise 
both  coloured  and  colourless  species,  but  the  latter  are  furnished  with 
leucoplasts.  Other  plastids  described  as  fat-forming  bodies  or  lipoplasts- 
are  also  met  with. 

The  vacuole-system  consists  of  saccules  and  pusules  discharging  into 
the  depression  from  which  the  Hagella  arise. 

The  excrescences  of  the  carapace  serve  as  floats  for  these  pelagic 
organisms  and  occur  as  linear  (Ceratium,  Fig.  11)  or  foliaceous 

FIG.  11. 

Ceratium  tripos.  Dorsal  view 
shortly  after  fission,  the  two 
daughter  individuals  still  at- 
tached to  each  other.  «,  the 
anterior  individual  protected 
by  the  greater  part  of  the 
parent's  epitheca ;  6,  the  pos- 
terior individual  protected  by 
the  greater  part  of  the  hypo- 
theca.  (After  Sohiitt.) 

FIG.  12. 

Peridiniu m  divergens.  Ventral  view 
.showing  the  vacuole-system.  c.p,  the 
small  collector-pusule  surrounded  by  :i 
rosette  of  still  smaller  pusules  which 
open  into  it;  s.p,  the  large  sac-pusule  or 
reservoir ;  both  opening  into  the  fundus 
(/),  from  which  both  the  transverse  flagel- 
lum  (0  lying  in  the  annulus  (a)  and  the 
longitudinal  flagellum  (/)  arise.  (After 

(Ornithocercus,  Fig.  10  (8))  expansions.  At  the  anterior  or  apical  end  of 
the  cell  there  is  an  apical  pore  which  is  frequently  closed  by  a  perforated 
plate  resembling  a  madreporic  plate  (e.g.  Blepharocysta}.  The  sulcus  is 
ventral,  but  there  is  no  plane  of  symmetry. 

Some  species  of  Ceratium  and  Peridinium  are  found  in  freshwater 
lakes,  but  the  other  genera  appear  to  be  exclusively  marine. 

In  respect  of  individual  numbers  the  principal  habitat  of  the  Peri- 
diniaceae  is  in  the  cold  waters  of  the  North  Sea,  Baltic,  and  North 
Atlantic.  In  point  of  specific  divergence  the  southern  waters  are  richer. 
Individual  variation  is  often  excessive,  and  seasonal  dimorphism  has  also 
been  noted. 

Genera  and  species  are  determined  by  the  form  of  the  body  and  by 
the  characters  of  the  cuirass. 

The  Peridiniaceae  are  divided  into  four  families  as  follows  : — 

FAMILY  1.  GLENODINIIDAE,  intermediate  between  Gymnodiniaceae  and 
Peridiniaceae.  Cuirass  soft,  membranous,  consisting  of  two  structureless- 


valves  with  an  anmilus  between  them.  Glenodinium  pulvisculus,  Ehrb. 
(Fig.  10  (3  and  4)). 

FAMILY  2.  PTYCHODISCIDAE.  Body  lens -shaped,  valves  perforate, 
annulus  soft,  membranous.  Ftychodiscus  nocticula,  Stein. 

FAMILY  3.  CERATIIDAE.  The  typical  genera  are  the  well-known 
forms  of  Ceratium  and  Peridinium.  The  valves  of  the  cuirass  are  described 
as  the  epitheca  and  the  hypotheca  respectively.  The  former  carries  the 
apical  pore  and  the  latter  the  sulcus.  But  the  sulcus  sometimes  extends 
beyond  its  decussation  with  the  annulus  up  the  ventral  side  of  the 
epitheca  to  the  apex  of  the  cell,  e.g.  in  Steiniella,  Schiitt,  and  Gonyaulax, 
Diesing  ;  or  the  sulcus  may  be  short,  extending  equidistantly  on  either 
side  of  the  annulus  as  in  Protoceratium,  Bergh. 

In  the  genus  Ceratium  we  meet  with  two-,  three-,  four-,  and  five- 
horned  varieties.  The  chromatophores  of  the  freshwater  species  of  the 
genus  are  green,  of  the  marine  species  yellowish  to  brownish  in  colour. 

Some  Ceratiidae  are  spherical,  as  Blepharocysta,  Ehrb.,  in  which  the 
annulus  and  sulcus  are  only  indicated  by  the  arrangement  of  the  plates. 
Closely  allied  to  Blepharocysta  is  the  genus  Podolampas,  St.,  which  has  a 
peridinioid  form  of  body  though  a  different  tabulation.  Others  are 
fusiform  like  the  remarkable  genus  Oxytoxum,  Stein.  In  Ceratocorys 
horrida,  Stein  (Fig.  10  (9)),  the  borders  of  the  annulus  are  expanded  like 
the  rim  of  a  hat,  while  the  left  sulcar  margin  is  expanded  into  a  wing 
bearing  long  plumose  spines.  Pyrophacus  is  an  oyster-shaped  Ceratian 
in  which  sporulation  has  been  observed  by  Schiitt.  The  new  genera 
Hderodininin,  Murrayella,  Acanthodinium  have  recently  been  described  by 

FAMILY  4.  DIXOPHYSIDAE.  The  shell  is  divided  by  a  sagittal  suture 
into  two  lateral  subequal  portions.  The  epitheca  is  flattened  and  much 
smaller  than  the  hypotlieca.  The  borders  of  the  annulus  are  funnel- 
shaped,  and  minute  brown-coloured  corpuscles  called  Phaeosomata  often 
occur  in  the  space  between  the  two  superimposed  funnels.  The  right 
sulcar  border  is  inconspicuous,  but  the  left  border  may  be  monstrously 
developed  into  wings  and  spines  (e.g.  Ornithocercus,  Fig.  10  (8)). 

In  Amphisolenia  (Fig.  10  (7))  the  epitheca  is  excessively  reduced,  consist- 
ing of  two  minute  plates  united  together  by  a  sagittal  suture.  The  dis- 
proportionately large  hypotheca  in  this  genus  consists  of  two  elongated 
plates  likewise  united  by  a  sagittal  suture.  The  sulcus  of  Amphisolenia 
(Fig.  10  (7))  proceeds  from  the  subterminal  annulus  along  the  neck  of  the 
cell  for  a  distance  equal  to  about  one-quarter  of  the  length  of  the  body, 
terminating  at  a  rather  deep  pit,  representing  the  depression  from  which 
the  flagella  arise  in  other  forms.  This  depression  may  be  conveniently 
distinguished  by  the  term  flagellar  fundus  or  simply  the  fundus.1 

In  AmphisQlcnia  the  protoplasmic  contents  of  the  cuirass  consist  of 
a  nucleus,  a  moniliform  chromatin  reticulum,  and  several  ellipsoidal 
plasmosomes  of  amyloid  character.  A  pusule  situated  near  the  nucleus 
opens  by  a  slender  canal  into  the  flagellar  pore,  and  one  or  more  accessory 
pusules  may  lie  near  it  in  the  cytoplasm. 

1  The  German  term  is  "Geisselspalte."     It  is  not  a  true  pharyngeal  pit  although 
it  strongly  resembles  one. 


Other  genera  of  Dinophysidae  are  Phalacroma,  St. ;  Dinophysis,  Ehrb.  ; 
Histioneis,  St.  (Fig.  10  (5,  6)),  Citharistes,  St.;  Triposolenia,  Kofoid — San 
Diego  region  of  the  Pacific. 


There  are  only  three  genera  in  this  sub-class,  and  of  these 
Nodiluca  has  long  been  known  as  a  widely  distributed  organism 
that  is  often  the  principal  cause  of  the  phosphorescence  of  the 
surface  of  the  sea.  The  other  two  genera  are  little  known. 

Nodiluca  possesses  a  sub-spherical  body  with  bilateral  symmetry, 
the  median  plane  of  symmetry  being  determined  by  an  elongated 
groove  on  the  ventral  side  called  the  peristome  (Fig.  15  (5)),  at  the 
bottom  of  which  is  the  mouth.  The  nutrition  is  holozoic,  and  the 
mouth  leads  directly  into  the  central  part  of  the  protoplasm,  from 
whence  trabeculae,  exhibiting  in  life  a  streaming  of  the  granules, 
radiate  outwards  towards  the  periphery.  In  certain  regions  the 
trabeculae  are  concentrated  in  the  form  of  dense  groups  of  fibrillae 
giving  rise  to  a  fibrillar  plexus.  One  such  plexus  arises  from  the 
posterior  end  (/)  of  the  central  protoplasm,  and  is  inserted  along  a 
thickened  linear  area  of  the  integument  behind  the  peristome  called 
the  bacillary  organ,  "Staborgan"  (Fig.  15  (5,  c)). 

The  integument  consists  of  a  resistent  ectoplasm,  a  dense 
reticulate  layer  of  alveolar  protoplasm.  The  striated  proboscis- 
like  tentacle  which  arises  in  the  middle  line  at  the  anterior  end 
of  the  peristome,  and  constitutes  one  of  the  most  notable  features 
of  its  organisation,  has  a  length  equal  to  half  the  diameter  of  the 
sphere.  It  is  a  flattened  contractile  organ,  convex  on  its  outer  side 
and  concave  on  the  inner  adoral  side.  The  protoplasmic  trabeculae 
which  traverse  the  tentacle  are  so  disposed  as  to  produce  a  striated 
structure  comparable  to  that  of  striped  muscle-fibres. 

Other  peristomial  organs  are  the  dentiform  process ;  the  flagellum, 
which  is  borne  upon  or  near  a  protuberance  termed  the  lip ;  and 
lastly  the  mouth.  The  tooth l  and  the  lip  are  placed  asymmetri- 
cally upon  the  right  wall  of  the  peristome.  The  mouth  occupies 
the  posterior  two-thirds  of  the  fundus  of  the  peristome,  which  is 
deepest  behind  and  becomes  progressively  shallower  in  front.  In 
front  of  the  mouth,  that  is  to  say,  in  the  anterior  third  of  the 
peristome,  are  the  lips,  with  the  flagellum,  the  tooth,  and  the 
tentacle.  The  flagellum  lies  well  within  the  peristome  and  requires 
practised  observation  for  its  discovery.2  It  resembles  the  typical 
flagellum  of  Mastigophora,  namely,  a  filament  of  uniform  thickness 
from  base  to  apex.  The  tentacle  can  be  extruded  far  beyond  the 
confines  of  the  peristome,  but  it  can  also  be  retracted,  rolled  up,  and 
so  escape  superficial  observation. 

'•  The  tooth  is  a  protoplasmic  organ.          -  It  was  discovered  by  Krohu  in  1852. 



The  nucleus  is  lodged  within  the  central  protoplasm,  and 
presents  during  life  a  transparent,  homogeneous  appearance. 

The  ingested  food  is  enclosed  in  food-vacuoles,  Avhich  are  some- 
times so  large  as  to  occupy  the  greater  portion  of  the  body.  No 
contractile  vacuole  has  been  observed.  The  products  of  metabolism 
consist  of  albuminoid  and  fatty  granules. 

Neither  the  slow  contractions  of  the  tentacle  nor  the  rapid 
vibrations  of  the  cilium  are  sufficient  to  impart  movements  of  pro- 
gression to  the  inert  body  of  Noctiluca,  which  merely  drifts  with  the 
rest  of  the  plankton,  kept  afloat  by  its  own  buoyancy.  The 

FIG.  13. 

Sporulation  by  blastogenesis  in  Noctiluca  miliaris,  Sur.  A,  surface  view  of  the  germinal 
disc,  showing  the  nuclei  that  give  rise  to  the  nuclei  of  the  spores.  Each  nucleus  (n)  is  accom- 
panied by  an  archoplasmic  body  (a).  B,  cleavage-products  (buds)  in  side  view.  C,  L>,  buds 
in  process  of  division.  The  archoplasmic  body  («)  is  seen  to  have  divided  before  the  nucleus 
(/().  K  and  F,  later  stages  of  blastogenesis.  (After  Doflein.) 

phosphorescence  of  Noctiluca  is  the  manifestation  of  its  response  to- 
mechanical,  electrical,  thermal,  and  chemical  stimuli.  According 
to  the  observations  of  Quatrefages  (quoted  by  Watase),  "  the  light 
emitted  from  the  whole  body,  or  any  of  its  parts,  is  composed  of  a, 
vast  number  of  instantaneous  scintillations." 

The  life-history  of  Noctiluca  comprises  the  phenomena  of  simple 
longitudinal  fission  (Fig.  15),  resting-phase,  conjugation,  and  blasto- 
genesis. The  transition  of  an  ordinary  individual  into  the  resting 
condition  does  not  involve  the  formation  of  a  protective  cyst- 
membrane,  but  simply  the  degeneration  of  the  peristome  and  its 

When  two  individuals  come  together  for  the  purpose  of  con- 


jugation,  they  attach  themselves  at  the  peristomial  region  and 
gradually  fuse  together  to  form  a  zygote  having  twice  the  normal 
volume.  The  fusion  of  the  nuclei  of  the  conjugants  has  been 
observed  directly,  under  the  microscope,  by  Cienkowski  and  later 
by  Plate. 

It  seems  likely,  although  still  awaiting  demonstration,  that  the 
production  of  swarm- spores  (zoospores)  by  exogenous  budding 
depends  upon  previous  conjugation. 

The  production  of  buds  is  limited  to  a  particular  area  of  the 
sphere,  namely,  the  area  corresponding  with  the  peristomial  region 

where  the  central  protoplasm  is  massed. 
The  cleavage  of  nucleus  and  protoplasm 
proceeds  in  a  manner  analogous  to  the 
discoidal  cleavage  of  a  yolk-laden  egg 
(Biitschli).  .Nearly  all  the  parent  pro- 
toplasm is  used  up  in  the  formation  of 
FIG.  14.  the  buds,  the  full  number  of  which 

Two    ripe    spores    of    Noctttum    amounts  to  512. 
mlliarls,    showing    n.    nucleus;    /',  m,  i     '  <•     i  i  • 

flageiium ;  6,  the  body  interpreted          Ihe  phenomena  of    karyokmesis  in 

to,be  a  blepharoblast  or  a  centro-  Nnriiliirn  Tvrpsjpnl-  cnmp  inrprpstino- 
some.  (After  Ishikawa.)  present  Testing 

features.  There  is  outside  the  nuclear 

membrane,  but  in  the  neighbourhood  of  the  nucleus,  a  relatively 
large  archoplasmic  body.  Before  division  of  the  nucleus  occurs, 
this  body  elongates  to  assume  a  dumb-bell  shape  (Fig.  3,  A),  Avith 
an  aster  at  each  end.  The  chromatin  of  the  nucleus  concentrates 
into  a  number  of  elongated  moniliform  chromosomes,  and  then  the 
nucleus  warps  itself  round  the  central  part  of  the  archoplasmic 
body,  forming  a  spindle-like  body  round  the  achromatic  spindle  of 
the  archoplasmic  body  (Fig.  3,  B).  Finally,  the  chromosomes 
divide  into  two  parties,  which  travel  to  the  opposite  poles  of  the 
spindle,  and  then  both  nucleus  and  archoplasm  divide  transversely. 

The  buds  project  from  the  surface  of  the  body,  but  remain 
attached  to  it  until  all  have  attained  a  certain  size,  and  until  each 
has  acquired  its  flagellum,  which  represents  the  cilium  of  the  adult 

The  detached  free-swimming  buds  have  a  dinoflagellate  appear- 
ance, and  it  may  be  broadly  stated  that  the  blastogenesis  of 
Nodiluca,  results  in  the  formation  of  gymnodiniform  young  (Fig. 
14).  The  growth  of  the  young  into  the  adult  condition  has  not 
been  observed. 

The  sub-class  contains  only  three  genera:  Nodiluca,  Suriray,  0'3-1'25 
mm.,  probably  cosmopolitan;  Leptodiscus,  Hertwig,  G'6-1'5  mm.  ;  and 
Craspedotella,  Kofoid  (8),  0'15-0'18  mm. — E.  Pacific.  Craspedotella  has 
a  strong  resemblance  to  a  craspedote  medusa  in  form,  being  bell-shaped 
and  having  a  distinct  velum  at  the  margin. 



Fio.  15. 

Nwtiluca  miliaris,  Suriray.  1,  2,  two  stages  in  the  longitudinal  lission  ;  n,  nucleus  ;  N, 
food  -  particles ;  t,  tentacle.  3,  aboral  view;  a,  entrance  to  the  peristome ;  c,  the  bacillary 
organ  ;  d,  the  tentacle ;  ft,  the  nucleus.  4,  the  animal  acted  upon  by  iodine  solution,  showing 
the  protoplasm  like  the  "primordial  utricle"  of  a  vegetable  cell  shrunk  away  from  the  cuirass. 
5,  lateral  view,  showing  (a)  the  entrance  to  the  peristome  in  which  6  is  placed  ;  <;,  the  bacillary 
organ  ;  <?,  the  tentacle  ;  e,  the  mouth  and  pharynx,  in  which  the  flagellum  is  situated  ;  /,  broad 
plexus  of  tibrillae  passing  from  the  central  protoplasm  to  the  bacillary  organs;  h,  nucleus. 
After  Lankester.) 


This  division  of  the  Mastigophora  affords  an  apparent  transition 
from  the  Flagellata  to  the  Radiolaria.  It  is  monotypic,  compris- 
ing the  single  species  Distephanus  speculum,  Stohr,  which  is  para- 
sitic upon  or  commensal  with  Radiolaria,  and  while  possessing  a 
flagellum,  has  also  a  fenestrated  siliceous  skeleton. 


Since  the  publication  of  Biitschli's  treatise  on  the  Mastigophora  in  Bronn's 
Klassen  und  Ordnungen  dcs  Tfiicrreichs,  Bd.  i.  Abth.  2,  1885,  this  class  of 
Protozoa  has  received  the  fullest  general  treatment  in  the  pages  of  Engler  and 


Fraud's  Die  naturlichen  Pflanzenfamilien,  where  the  Flagellata  have  been 
written  upon  by  G.  Senn  (Leipzig,  1900)  ;  the  Peridiniales  by  F.  Schiitt  (1896) ; 
and  the  Volvocaceae  by  N.  Wille.  Further  references  will  be  found  in  the 
bibliography  appended  to  the  volume  on  the  Protozoa  by  G.  N.  Calkins  in  the 
Columbia  University  Biological  Series  (1901). 

In  the  following  list  will  be  found  references  to  some  of  the  principal  papers 
mentioned  in  the  text : — 

1.  Apstein,  C.     Pyrocystis  lunula.     Lab.  inter.  Meeresforsch.  Kiel,  viii.,  1906, 

p.  263. 

2.  Biackman,  F.  F.,  and  Tansley,  A.  G.     A  Revision  of  the  Classification  of 

the  Green  Algae.     New  Phytol.  i.,  1902. 

3.  Dobell,  C.  C.     Structure  and  Life-History  of  Copromonas.     Q.  J.  Micr.  Sci. 

lii.,  1908,  p.  75. 

4.  Goldschmidt,  R.     Lebensgeschichte  der  Mastigambben.     Arch.  Prot.  Suppl., 

1907,  p.  83. 

5.  Hartman,    M.,    and    von    Prowazek,    S.      Blepharoblast,    Caryosom    und 

Centrosom.     Arch.  Prot.  x.,  1907,  p.  307. 

6.  Hickson,  S.  J.     Reproduction  and  Life-History  of  the  Protozoa.     Trans, 

Manch.  Micr.  Soc.,  1900. 

7.  Keeble,  F.  W.,  and  Gamble,  F.  W.     The -Green  Cells  of  Convoluta.     Q.  J. 

Micr.  Sci.  li.,  1907,  p.  167. 

8.  Kofoid,  C.  A.     Craspedotella.     Bull.  Mus.  Harvard,  xlvi.  9,  1905. 

9.  New  Species  of  Dinoflagellates.     Ibid.  1.  6,  1907. 

10.   Dinoflagellata   of  San   Diego.      Univ.    California    Pub.    Zool.   ii.    8, 

1906  ;  Hi.  6,  7,  and  8,  1906  ;  and  Hi.  13,  1907. 

10a.  Polykrikos.     Zool.  Anz.  xxxi.,  1907,  p.  291. 

11.  Lohmann,  If.     Die  Coccolithophoridae.     Arch.  Prot.  i.,  1902,  p.  89. 

12.  Lotsy,  J.  P.     Vortrage  liber  botanische  Stammesgeschichte.     Jena,  1907. 

13.  Minchin,    A.  E.      Investigations  on   the   Development   of  Trypanosomes. 

Q.  J.  Micr.  Sci.  Hi.,  1908. 

14.  Moore,  J.  E.  S.     The  Cytology  of  the  Trypanosomes.     Ann.  Trop.  Med.  i., 


15.  Murray,  G.,  and  Blackman,  V.  H.     The  Nature  of  the  Coccospheres  and 

Rhabdospheres.     Phil.  Trans,  vol.  cxc.,  1898,  p.  427. 

16.  Prowazek,  S.  von.     Flagellatenstudien.     Arch.  Prot.  ii.,  1903,  p.  195. 

17.  Untersuchungen    iiber    einige     parasitische    Flagellaten.      Arb.    k. 

Gesundheitsamte,  xxi.,  1904,  p.  1. 

18.  Robertson,  M.     Pseudospora  volvocis.     Q.  J.  Micr.  Sci.  xlix.,  1905,  p.  213. 

19.  Schaudinn,  F.     Generations-  und  Wirtswechsel  bei  Trypanosoma.     Arb.  k. 

Gesundheitsamte,  xix.,  1902,  p.  169. 

20.  Untersuchungeu  iiber  die  Fortpflanzung  einiger  Rhizopoden.     Ibid. 

1903,  p.  547. 

21.  Wenyon,  C.  M.     Observations  on  the  Protozoa  in  the  Intestines  of  Mice. 

Arch.  Prot.  Suppl.,  1907,  p.  169. 

22.  West,  G.  S.      A  Treatise  on  the  British   Freshwater  Algae.      Cambridge, 


23.  Woronin.     Chromophyton  rosanqffii.     Bot.  Ztg.,  1880. 

24.  Zederbauer,  E.      Geschlechtliche   u.   ungeschlechtliche  Fortpflanzung   von 

Ceratiwn.     Ber.  d.  D.  bot.  Gesell.  xxii.  1,  1904. 

THE  PROTOZOA  (continued) 


Order  Lissoflagellata.2 
Sub-Order  MONADINA. 

Genus  Trypanomorpha. 


Genera  Trypanophis,  Trypanoplasma, 
and  Trypanosoma. 


THE  Haemoflagellates,  or  Trypanosomes,  although  possessing  in 
common  a  uniform  type  of  organisation,  probably  do  not  all  belong 
to  a  single,  well-defined  group  of  monophyletic  origin.  They  are 
preferably  regarded  as  an  assemblage  of  forms  which  have  sprung 
from  two  quite  different  stocks,  the  resemblances  exhibited  being 
due  to  convergence,  brought  about  by  the  acquirement  of  similar 
adaptations  in  response  to  their  similar  and  highly  specialised  mode 
of  life.  They  are  entirely  parasitic,  their  characteristic  habitat 
being  the  blood  of  a  Vertebrate ;  and,  as  is  well  known,  certain  of 
them  are  the  cause  of  severe,  often  fatal  illness. 

The  Haemoflagellates  possess  either  one  or  two  flagella.  When 
there  are  two,  they  originate  close  together,  at  or  near  the  anterior 
end  of  the  body.  One  is  free  and  directed  forwards ;  the  other 
turns  back  and  is  attached  for  the  greater  part  of  its  length  to  the 
side  of  the  body,  by  means  of  an  undulating  membrane,  ultimately 
terminating  in  a  free  portion  directed  posteriorly.  Thus  a  Hetero- 
mastigine  condition  is  found.  When  only  one  flagellum  is  present 

1  By  H.  M.  Woodcock,  D.Sc.  (Loud.),  Assistant  to  the  University  Professor  of 

2  The  classification  of  the  Flagellates  here  made  use  of  differs  somewhat  from  that 
adopted  in  the  account  of  the  Mastigophora.      The  position  of  the  Trypanosomes 
according  to  that  scheme  will  be  seen  on  reference  to  pp.  167,  168. 

193  13 



it  is  invariably  attached  in  this  manner,  but  the  flagellum  is 
probably  not  homologous  in  all  these  cases.  In  certain  Trypano- 
somes  which  are  to  be  derived  from  a  Monadine  ancestor,  it  is,  of 
course,  the  single  flagellum  that  is  represented,  with  the  free  part 
directed  anteriorly  ;  other  forms,  however,  are  rather  to  be  looked 
upon  as  derived  from  a  Heteromastigine  ancestor,  the  flagellum 
that  persists  being  the  trailing,  posteriorly  directed  one  (the 
so-called  "  Schleppgeissel").1  There  are  two  nuclear  bodies,  one, 
the  trophonucleus,  regulating  the  trophic  life  of  the  cell,  the  other, 
the  kinetonucleus,  directing  its  locomotor  activities. 

FIG.  1. 
"  Undulina  ranarum,"  Lankester,  1871.     In  13  the  nucleus  is  shown. 

The  most  general  method  of  reproduction  is  by  binary,  longi- 
tudinal fission  ;  but  multiple  division  or  segmentation  is  also  met 
with.  As  regards  the  life-cycle  of  the  parasites,  only  little  is  as 
yet  known  in  most  cases.  From  the  results  of  the  most  recent 
researches,  however,  it  certainly  appears  probable  that,  apart  from 
various  blood  -  sucking  Invertebrates  which  may  (mechanically) 
transmit  a  given  parasite,  there  is,  in  general,  a  true  alternate  host 
for  each  form ;  one,  that  is,  in  which  definite  phases  of  the  life- 
cycle — including,  most  likely,  sexual  conjugation — are  normally 
undergone.  Further  knowledge  on  this  subject  is  greatly  needed. 

Historical. — The  first  observation  of  a  Trypanosome  is  probably 
to  be  ascribed  to  Valentin,  who,  in  1841,  announced  his  discovery 

1  This  flagellum  is  also  termed  the  gubernaculum  (see  p.  159). 



of  Amoeba-\ike  parasites  in  the  blood  of  a  trout.  In  the  two  or 
three  years  following,  Remak,  Berg,  and  others  recorded  the 
occurrence  of  Htiematozoa  which  were  undoubtedly  Trypanosomes 
in  different  fishes.  The  parasite  of  frogs  was  first  seen  by  Gluge 
(1842),  and  in  July  1843  Mayer  described  and  figured  certain 
corkscrew-like  and  amoeboid  organisms  from  the  blood  of  the  same 
animal,  which  he  termed  variously  Amoeba  rotatoria  and  Paramoecium 
costatmn  or  loricatum.  A  few  months  later  (November)  Gruby  also 
published  (24)  an  account  of  this  parasite,  to  which  he  gave  the  new 
generic  name  of  Trypanosoma.  The  same  form  was  subsequently 
described  and  figured  by  Lankester  (30)  in  1871,  who,  unaware  of 
Gruby 's  work,  called  it  Undulina  ranarum ;  this  author  was  the 
first  to  indicate  the  presence  of  a  nucleus  in  the  organism  (Fig.  1,  B). 
The  well-known  parasite  of  rats  was  discovered  by  Lewis,  in  India,  in 
1878,  and  was  afterwards  named  Herpetomonas  lewisi  by  Kent.1  It 
is  to  Mitrophanow  (1883  to  1884)  and  Danilewsky  (1885  to  1889), 
however,  that  we  owe  the  first  serious  attempts  to  study  the  com- 
parative anatomy  of  these 
Haematozoa.  The  work  of 
the  latter  researcher  in  par- 
ticular is  deserving  of  recog- 
nition, especially  when  the 
primitive  state  of  knowledge 
in  regard  to  blood-technique 
in  those  days  is  borne  in 
mind.  Some  of  Danilewsky's 
figures  of  a  Trypanosome  of 
birds  are  reproduced  in  Fig.  2. 
Trypanosomes  were  first 
met  with  in  cases  of  disease 
by  Griffith  Evans,  who,  in 
1880,  found  them  in  the  blood 
of  horses  suffering  from  Surra 
in  India.  The  organisms  were 
thought  by  him  to  be  Spirilla. 
Steel  rediscovered  the  same 
form  a  few  years  later  and 
took  a  similar  view  of  its 
affinities,  naming  it  Spirochaeta 
evansi.  In  1894  Bruce  found  the  celebrated  South  African  parasite 
( T.  bnicii)  in  the  blood  of  cattle  and  horses  laid  low  with  Nagana, 
or  Tsetse-fly  disease ;  and  this  worker  subsequently  demonstrated, 
in  a  brilliant  manner,  the  essential  part  played  by  the  fly  in  trans- 
mitting the  parasite.  Brace's  discovery  may  be  said  to  have 
inaugurated  a  rapid  increase  in  the  number  of  known  forms,  the 

1  This  form  is  now  placed  in  the  genus  Trypanosoma. 

A-C,  different  forms  of  Trypanosoma,  sangulnis 
avium,  Danilewsky.  D,  the  same  parasite  dividing 
longitudinally .  n,  nucleus  ;  u.m,  undulating  mem- 
brane ;  /,  nagellum.  (After  Danilewsky.) 


knowledge  of  which  has  in  many  cases  thrown  light  upon  the 
etiology  of  maladies  previously  obscure.  Thus,  two  characteristic 
diseases,  Dourine,  which  afflicts  horses  and  mules  in  Northern 
Africa  and  the  Mediterranean  littoral,  and  Mai  de  Caderas  of 
horses  in  South  America,  were  next  shown  to  be  caused  by 
different  Trypanosomes ;  and  since  then  many  other  varieties  of 
trypanosomosis  have  been  described,  chiefly  from  Africa,  the  home 
of  the  dreaded  Tsetse-fly. 

Prominent  among  them,  unfortunately,  is  human  trypanosomosis. 
The  credit  for  first  recognising  a  Trypanosome  in  human  blood, 
and  describing  it  as  such,  must  undoubtedly  be  assigned  to  Nepveu 
(1898).  The  parasites  were  not  definitely  associated  with  disease, 
however,  till  1901,  when  they  were  seen  in  the  blood  of  a  European 
in  Senegambia  suffering  from  intermittent  fever.  Forde  first  found 
the  organisms,  but  was  uncertain  of  their  nature ;  he  showed  them 
to  Button,  who  recognised  them  as  Trypanosomes,  and  gave  this 
form  the  name  of  Trypanosoma  gambiense.  A  year  later  (1902) 
Castellani  discovered  what  has  been  shown  to  be  the  same  parasite  in 
the  cerebro-spinal  fluid  of  patients  suffering  from  sleeping-sickness 
in  Uganda,  and  it  has  since  been  conclusively  proved  by  Bruce 
and  Nabarro  that  this  organism  is  the  true  cause  of  that  terrible 

More  important,  however,  from  the  standpoint  of  Protozoology, 
than  these  interesting  medical  discoveries  have  been  the  investigations 
by  Brumpt,  Laveran  and  Mesnil,  Le"ger,  Minchin,  Schaudinn,  the 
Sergents,  and  others  during  the  last  few  years  upon  numerous  other, 
mostly  "  tolerated  "  forms ;  to  their  researches,  indeed,  we  owe  most 
of  our  knowledge  at  the  present  time,  relating  to  the  life-cycle  of 
the  Haemoflagellates.  And  it  is  fitting,  here,  to  pay  a  tribute  to 
the  value  of  the  characteristic  stain  first  made  known  by  Roman- 
owsky,  and  its  subsequent  modifications  (e.g.  those  of  Giemsa, 
Laveran,  Leishman,  etc.),  without  which,  it  is  safe  to  say,  thi» 
progress  would  have  been  impossible. 



(a)  Occurrence  and  Transmission. 

Trypanosomes  are  harboured  by  members  of  all  the  chief  classes 
of  Vertebrates,  with  the  exception  of  Cyclostomes.  Mammals,  birds, 
and  fishes  furnish,  however,  by  far  the  greater  number  of  hosts.  Fewer 
parasites  have  been  described  from  Amphibia,  and  up  till  now  only 
from  frogs  ;  while,  among  Reptiles,  their  occurrence  has  only  been 
observed  in  two  or  three  instances.  Data  with  regard  to  the 
frequency  with  which  individual  species  are  to  be  met  with,  in  any 


particular  kind  of  host,  are  as  yet  somewhat  scanty.  In  one  or 
two  cases,  however,  the  parasites  are  known  to  be  fairly  common. 
Trypanosoina  lewisi,  for  example,  occurs  in  a  considerable  percentage 
of  sewer -rats  throughout  the  world,  having  accompanied  these 
rodents  in  their  ubiquitous  migrations ;  the  proportion  of  hosts 
infected  varies  usually  from  10  to  40  per  cent. 

In  considering  the  occurrence  of  Trypanosomes  in  Mammals 
careful  distinction  must  be  drawn  between  true  or  natural  hosts 
and  strange  or  casual  ones.  In  the  former  case,  by  reason  of  the 
long-existing  association  between  host  and  parasite,  a  condition  of 
mutual  toleration  has  been  reached,  which,  in  ordinary  circum- 
stances, enables  a  proper  balance  to  be  maintained  on  both  sides. 
On  the  other  hand,  when  a  Trypanosome  gains  an  entry  into 
animals  Avhich  have  never  been  previously  liable,  by  their  dis- 
tribution, to  its  invasion,  and  which  are  consequently  unaccustomed 
and  unadapted  to  the  organism,  it  usually  produces  markedly 
harmful  effects.  Such  a  state  of  affairs  has  resulted,  for  example, 
from  the  march  of  civilisation  into  the  "  hinterlands "  of  the 
various  Colonies,  where  man,  together  with  the  numerous  domestic 
animals  which  accompany  him,  has  been  brought  into  proximity  to 
big  game,  etc.,  and  what  is  equally  important,  into  the  zone  of  the 
blood-sucking  insects  which  prey  upon  the  same. 

Very  many  of  the  common  domestic  Mammals  can  be  success- 
fully infected  (either  in  an  accidental  way  or  else  artificially)  with 
different  "  pathogenic "  Trypanosomes,  to  which  they  succumb 
more  or  less  readily ;  they  cannot  be  regarded,  however,  as  natural 
hosts  of  those  Trypanosomes.  In  considering  disease-causing  forms, 
the  more  narrowly  the  original  source  of  the  parasite  concerned  is 
defined,  the  closer  do  we  get  to  the  true  Vertebrate  host  or  hosts. 
In  the  case  of  the  Nagana  parasite,  it  has  been  shown  that  such  are 
almost  certainly  to  be  found  among  buffaloes  and  various  Antilo- 
pidae  (e.g.  the  gnu,  "koodoo,"  etc.),  while,  again,  the  native  host  of 
T.  equinum,  of  Mai  de  Caderas  in  South  America,  is  most  probably 
the  capybara.  It  may  be  said  undoubtedly,  with  regard  to  the 
many  lethal  Trypanosomes  now  known,  that  there  is,  in  each  case, 
some  indigenous  wild  animal  tolerant  of  that  particular  form, 
which  serves  as  a  latent  source  of  supply  to  strange  Mammals 
coming  into  the  vicinity. 

Transmission. — In  the  transmission  of  the  parasites  from  one 
Vertebrate  individual  to  another,  a  blood-sucking  Invertebrate  is 
almost  invariably  concerned.1  In  the  case  of  all  Trypanosomes  of 

1  Trypanosoina  equiperdum,  the  cause  of  Dourine  or  horse-syphilis,  is  conveyed  by 
the  act  of  coitus  ;  and  it  is  quite  uncertain  whether  this  parasite  is  ever  transmitted 
naturally  by  an  insect.  Moreover,  Koch  has  recently  brought  forward  evidence 
(29,  Schluss  -  Bericht)  which,  he  thinks,  tends  to  show  that  the  human  parasite 
(T.  gambiense)  can  also  lie  transmitted  by  sexual  intercourse. 


warm-blooded  Vertebrates  for  which  the  transmitting  agent  is 
known,  this  is  an  insect,  generally  a  member  of  the  Diptera ;  in 
that  of  Trypanosomes  of  cold-blooded  Vertebrates  the  same  role  is 
usually  played  by  an  Ichthyobdellid  leech  (Piscine  forms),  but 
possibly  now  and  again  by  an  Ixodes  (some  Amphibian  or  Eeptilian 

The  actual  relation  between  the  parasite  and  the  transmitting 
Invertebrate  has  long  been  questioned,  and  there  are  still  some 
very  important  instances  in  which  the  real  state  of  affairs  is  not 
certain.  But  it  would  seem,  from  the.  results  of  recent  work, 
that  in  most  cases  some  Invertebrate  or  other  acts  as  a  true 
alternate  host.  Thus,  so  far  as  leeches  are  concerned  in  connec- 
tion with  the  Trypanosomes  of  fishes,  the  investigations  of  Leger 
(50),  Brumpt  (10-12),  and  Keysselitz  (27)  have  made  it  clear  that 
the  parasites  not  only  live  quite  normally,  but  undergo  a  definite 
evolution  in  particular  organs  of  leeches  which  have  fed  on  infected 
fish.  Frequently  this  further  development  can  only  proceed,  at 
least  to  its  full  extent,  in  a  certain  leech  to  the  exclusion  of  others 
(e.g.  in  a  Hemiclepsis  and  not  in  a  Piscicola,  or  vice  versa) ;  this  restric- 
tion points  distinctly  to  the  leech  in  question  being  a  specific  natural 
host.  Again,  according  to  the  celebrated  researches  of  Schaudinn 
(75)  on  an  Avian  Trypanosome,  Trypanomarpka  (Trypanosoma) 
noctuae,  a  species  of  gnat  (Culex)  provides  the  alternate  host, 
in  which  a  complex  part  of  the  life -cycle  takes  place.  It  is 
interesting  to  note  that,  as  might  be  expected,  there  is  a  regular 
periodicity  in  the  infectivity  of  the  gnat ;  that  is,  it  can  only 
transmit  the  infection  after  such  and  such  an  interval  has  elapsed 
since  the  meal  when  it  became  itself  infected.  Coming,  lastly,  to 
the  Mammalian  forms,  Prowazek  (68)  has  described  phases  of 
development  of  T.  lewisi  in  the  rat-louse  (Haematopinus  sp.), 
and  considers  that  this  insect  serves  as  a  true  Invertebrate  host ; 
though  he  was  not  able  to  prove  the  actual  transmission  of  the 
parasites  back  to  the  rat  by  means  of  it.1 

Interest  and  discussion  has  mostly  centred,  however,  upon  the 
part  played  by  the  transmitters  of  the  lethal  Trypanosomes,  and 
it  is  only  quite  recently  that  any  light  can  be  said  to  have  been 
thrown  upon  the  subject. 

It  has  for  some  time  been  generally  recognised  that,  in  many  cases  at 
any  rate,  a  particular  biting-fly  is  chiefly  responsible  for  the  spread  of  a 
particular  parasite  in  an  infective  district.  In  such  cases,  a  striking 
coincidence  usually  exists  between  the  area  over  which  a  certain  trypanoso- 
mosis  is  prevalent  and  the  zone  of  distribution  of  a  certain  fly.  Thus,  of 
two  well-known  African  Trypanosomes,  one,  T.  briicii,  the  cause  of  Nagana 

1  This    has    been    effected,    however,    by   earlier    observers   (Rabinowitsch    and 
Kempner)  by  means  of  fleas,  which  are  possibly  the  "  right  "  insects. 



or  Tsetse-fly  disease  in  South-East  Africa,  is  conveyed  by  Glossina  morsitans  l 
(Fig.  3,  A  and  B),  while  the  other,  T.  gambieiise,  the  cause  of  sleeping- 
sickness,  has  for  its  carrier  in  Uganda  another  Tsetse-fly,  G.  palpalis. 

Working  upon  this  knowledge,  many  investigators  have  at  one  time 
or  another  performed  series  of  experiments  with  a  view  to  finding  out 
whether  any  developmental  cycle  is  undergone  by  the  parasites  while  in 
the  fly,  and  whether  definite  periods  of  infectivity  occur,  on  the  analogy 
of  the  malarial  parasites  in  mosquitoes.  The  earlier  results  obtained 
seemed  to  indicate  that  the  role  of  the  fly  was  purely  mechanical — the 
insect  acting  merely  like  an  artificial  inoculating  tube.  Bruce,  in  the 
course  of  his  pioneer  work  in  Zululand,  found  that  the  flies  could,  with 


Various  blood-sui-king  flics.  A  and  B,  Glossina  morsitans  (transmits  Trypanosmna  brurii, 
of  Nagana),  x  2  ;  C,  Hipi>(H>oscu  rufipes  (thought  to  transmit  T.  thdleri,  the  cause  of  "  bile-sick- 
iii-ss"),  x  U;  I),  Tn.lH.inns  Uneola  (probably  conveys  the  Surra  parasite,  T.  evansi),  x  1J ;  E, 
Mnitin.Ti/.- -i-ii],  -itfi'na (suspected  in  connection  with  T.  equinvm,  of  Mai  de  Caderas),  x  2J.  (A  and 
B  from  Lav.  and  Mesn.,  after  Bruce ;  C  after  L.  and  M.  ;  D  and  B  after  Salmon  and  Stiles.) 

varying  success,  infect  a  healthy  animal  if  allowed  to  bite  it  up  to  forty- 
eight  hours  after  being  themselves  fed  on  an  infected  one,  but  not  after- 
wards. Similarly,  Bruce,  Nabarro,  and  Greig  (8)  ascertained  that  G. 
palpalis  could  give  rise  to  an  infection  ei«ht,  twenty-four,  or  forty-eight 
hours  after  feeding,  but  after  two  days  they  could  no  longer  obtain  a 
successful  inoculation.  Moreover,  some  experiments  extended  over  two 
months  gave  no  sign  of  any  periodicity  of  infection.  Nevertheless,  these 
workers  found  that  the  Trypanosomes  could  at  all  events  live  and  retain 
their  mobility  in  the  stomach  of  the  fly  up  to  seventy-one  hours. 

Similar  results  were  obtained  by  Minchin,  Gray,  and  Tulloch.  In 
their  interesting  report  (59)  these  authors  state  that  they  could  find 
no  evidence  of  a  fly  becoming  infectious  at  any  particular  period  after 

1  Tliis  parasite  is  also  conveyed,  in  different  districts,  by  G.  pallidipe!!  and 


being  fed,  experiments  being  carried  out  up  to  an  interval  of  twenty-two 
days.  An  additional  and  significant  fact  remarked  upon  by  them  is  that 
only  the  first  animal  which  the  experimental  fly  was  allowed  to  stab 
became  infected  ;  if  the  insect  was  removed  before  its  meal  was  completed 
and  immediately  placed  on  another  animal,  this  latter  did  not  become 
infected.  That  is  to  say,  after  a  fly  had  been  allowed  to,  as  it  were,  clean 
its  proboscis  from  the  Trypanosomes  remaining  in  it  since  its  previous 
meal  (on  an  infected  animal),  it  was  no  longer  infectious. 

These  facts  make  it  certain  that  Trypanosomes  can  be  and  are 
conveyed  by  Tsetse-flies  in  a  purely  direct  and  mechanical  manner ; 
and  so  far  as  T.  gambiense  and  sleeping-sickness  in  Uganda  are 
concerned,  it  is  probable  that  their  spread,  through  the  agency  of 
G.  palpalis,  has  been  largely  if  not  entirely  in  this  way.  But  this 
does  not  by  any  means  end  the  matter. 

Minchin,  Gray,  and  Tulloch  bring  forward  observations  which 
point  to  a  commencing  cycle  of  development  of  T.  gambiense 1  in  the 
fly.  Up  to  forty-eight  hours  the  Trypanosomes  present  in  the 
stomach  of  an  infected  fly  are  markedly  differentiated  into  two 
types,  which  probably  represent  sexual  forms.  After  forty-eight 
hours  a  type  of  more  indifferent  character  makes  its  appearance, 
which  usually  becomes  scanty  with  lapse  of  time,  till  at  ninety-six 
hours  scarcely  a  Trypanosome  can  be  found.  It  is  interesting  to 
note  that  during  this  interval  the  parasites  steadily  increase  in 
size.  Coming  next  to  Koch's  recent  investigations  on  behalf  of 
the  German  Sleeping- Sickness  Commission,  a  very  important 
observation  is  recorded  (29).  A  species  of  Glossina,  distinct  from 
G.  palpalis,  namely,  G.  fusca,  was  bred  in  captivity  ;  the  individuals 
born  and  reared  under  these  conditions  were  regarded  as  certainly 
free  from  Trypanosomes.2  Several  of  these  flies  were  fed  on  rats 
infected  with  T.  gambiense.  They  were  examined  from  ten  to 
twelve  days  later,  and  after  this  long  interval  were  found  to  be 
infected  with  those  parasites.  Moreover,  individuals  of  another 
Tsetse-fly,  G.  tachinoides,  similarly  fed,  were  also  found  to  contain 
T.  gambiense  after  the  same  lengthy  interval. 

Still  more  recently  Stuhlmann  (80),  in  his  description  of  G. 
fusca,  has  published  some  extremely  interesting  notes  on  the  relation 
of  T.  bnicii  to  this  fly.  Using  reared  flies,  considered  to  be  certainly 
free  from  infection,  Stuhlmann  was  able  to  infect  about  80  to  90 

1  The  case  of  T.  gambiense  in  Glossina  palpalis  is  unfortunately  complicated  by 
the  occurrence  in  the  same  species  of  fly  of  other  Trypanosomes,  distinguished  by 
Novy(61)  as  "  fly-Trypanosomes. "     One  of  these,  T.  grayi,  at  any  rate  is  entirely 
ditferent  from  T.  ganibiense  ;  and  it  is  highly  probable  that  some  of  the  observers  (e.g. 
Gray  and  Tulloch   [23],  Koch  [28]),   who  first  described  what  they  regarded   as 
developmental  phases  of  T.  gambiense,  were  dealing  in  reality  with  T.  grayi. 

2  This  is  on  the  assumption,  of  course,  that  the  parasites  were  not  inherited  ;  but 
most  authorities  seem  to  be  agreed  that  hereditary  transmission  of  Trypanosomes  by 
Tsetse-flies  does  not  take  place. 


per  cent,  and  in  from  two  to  four  days  was  able  to  observe  various 
developmental  phases  of  the  parasites.  This  further  development 
continued  on  the  flies  being  fed  upon  healthy  animals,  but  only  in 
about  10  per  cent  of  the  individuals  ;  in  the  rest  it  gradually  dis- 
appeared. This  percentage,  it  is  instructive  to  observe,  was  about 
the  same  as  that  of  the  Tsetses  (G.  fusca)  found  to  be  infected  with 
T.  brucii  (in  all  probability)  in  nature. 

It  will  be  seen  that  it  is  impossible  to  draw  any  certain  con- 
clusions from  the  present  position  of  the  problem.  Nevertheless, 
there  is  good  reason  to  suppose  that,  for  a  given  lethal  Trypano- 
some,  there  is  a  particular  insect  which  is  a  true  alternate  host.1 
It  seems  very  probable  that  here,  as  among  leeches,  there  are 
right  and  wrong  hosts  for  the  parasites ;  that  while  the  com- 
plete normal  development,  culminating  in  the  transfer  back  to  the 
Vertebrate,  can  only  take  place  in  a  certain  species  of  fly,  attempts 
at  development  which  are,  to  a  varying  degree,  partially  successful 
may  go  on  in  other  biting- flies ;  these  latter,  however,  being 
able  to  act  in  relation  to  the  Vertebrate  host  only  as  mechanical 

Before  leaving  this  question  of  the  mode  of  transmission  of 
Trypanosomes,  it  is  to  be  noted  that  Minchin  has  put  forward  (57) 
an  entirely  new  view  with  regard  to  the  method  of  infection.  His 
idea  is  based  especially  upon  the  highly  interesting  discovery  made 
by  him  of  the  occurrence  of  cysts,  doubtless  for  external  dissemina- 
tion by  way  of  the  anus,  in  one  of  the  "  fly  -  Trypanosomes," 
Trypanosoma  grayi.  Minchin  suggests  that  there  may  be  two 
varieties  of  cyclical  infection  among  the  Haemoflagellates ;  in  the 
.one,  the  parasite  undergoes  cyst-formation  in  the  insect,  resulting 
in  a  contaminative  infection  of  the  Vertebrate,  by  means  of  its  food 
or  drink ;  in  the  other,  distinguished  as  the  inoculative  type,  the 
infection  takes  place  through  the  proboscis  of  the  fly  (as,  for 
example,  in  the  malarial  parasites).  Up  to  the  present,  however, 
T.  grayi  remains  the  only  known  form  in  the  case  of  which  infection 
is  most  probably  of  the  first  type.2  From  what  has  been  learnt  so 
far  of  the  development  of  other  Trypanosomes — Avhether  in  leeches 
or  in  insects — the  distribution  of  the  parasites  in  the  body  (see 
under  "  Habitat")  points  at  any  rate  to  inoculative  infection  of  the 
Vertebrate.  The  possibility  of  the  occurrence  of  both  modes  in  any 
.one  Trypanosome  is  not,  so  far  as  is  known,  excluded ;  but  there 
is,  as  yet,  no  definite  evidence  in  favour  of  this. 

1  For  further  remarks  bearing  on  this  point,  see  pp.  230-231,  261. 

2  Although  the  Vertebrate  host  of  T.  grnyi  has  not  been  actually  demonstrated, 
both  Minchin  and  others  have  made  an  important  observation  in  connection  with  the 
biology  of  the  Tsetse-tty,  which — taken  in  conjunction  with  the  non-occurrence  of 
hereditary  infection— seems  to  show  that  it  is  impossible  for  the  parasites  to  be 
merely  fly-Trypanosomes.      This  is  to  the  effect  that  the  Tsetses,  unlike  mosquitoes, 
/eed  only  on  blood,  never  on  foul  or  decaying  matter  of  any  kind. 


(b)  Habitat  and  Effects  on  Ho.<f. 

1.  Relation  to  the  Invertebrate  Host. — Schaudinn,  in  his  work  on 
the  parasites  of  an  owl  (Athene  noctua)  (I.e.),  has  described  in  full 
the  distribution  and  course  of  development  of  Trypanosomes  in  the 
body  of  a  gnat  (Culex  pipiens).  Although,  as  is  pointed  out  below 
(see  under  "Life-Cycle"),  it  is  now  disputed  how  far  Schaudinn's 
description  actually  relates  to  Avian  Trypanosomes,  the  great 
interest  excited  by  this  author's  work  renders  a  brief  abstract  of 
his  account  necessary. 


Fie.  4. 

Diagrammatical  longitudinal  section  through  Culex  pipiens  to  show  the  distribution  of  thff 
parasites.  The  arrows  indicate  the  direction  of  their  movement,  the  cTusters  of  stars  the  place* 
of  agglomeration,  u.l,  upper  lip  ;  LI,  lower  lip;  tip,  hypopharynx  ;  ph,  pharynx;  s.g,  salivary 
gland ;  ocs,  oesophagus ;  o.d,  oesophageal  diverticula  (gas  reservoirs) ;  prov,  proventriculus  ; 
st,  stomach ;  m.t,  Malpighian  tubes ;  c,  junction  of  ileum  and  colon  ;  aort,  aorta.  (After 

The  distribution  of  the  parasites 1  is  intimately  connected  with  the 
process  of  digestion.  Towards  the  end  of  the  digestion  of  the  imbibed 
blood,  the  Trypanosomes,  after  a  period  of  multiplication,  enter  upon  ;v 
resting  phase,  and  are  found  either  attached  to  or  between  the  epithelial 
cells.  After  a  second  meal  another  multiplicative  period  occurs,  and  the 
parasites  gradually  collect  in  the  anterior  part  of  the  stomach,  where  the 
nutriment  remains  longest  unabsorbed.  Here  (Fig.  4,  prov)  the  organisms 
begin  to  cluster  in  large  numbers,  being  able  to  penetrate  the  delicate 
surface  of  the  layer  of  invaginated  oesophageal  epithelium  in  this  region. 
Finally,  there  is  an  enormous  accumulation  of  the  Trypanosomes  at  this 
place,  all  arranged  in  rows  and  in  a  resting  condition.  The  next  inflow 

1  Tliis  summary  relates  to  the  first  of  the  two  parasites  described  by  Schauiliim, 
Trypanomorptia  (Trypanosoma}  noctnae. 


of  blood  drives  this  mass  before  it,  in  the  form  of  a  rolled-up  ball,  until 
it  reaches  the  junction  of  the  ileum  and  colon  (Fig.  4,  c),  the  narrowest 
point  of  the  intestine.  The  wall  here  is  very  thin  and  easily  ruptured, 
and  most  of  the  Trypanosomes  pass  through  it,  into  the  vascular  lacunae 
around,  whence  they  are  carried  to  the  heart.  Finally,  the  parasites 
become  arrested  in  the  sinus  surrounding  the  pumping-organ  of  the 
pharynx,  where  they  continue  to  multiply  and  collect  again  into 
agglomerated  masses,  which  press  on  the  wall  of  the  pharynx  in  this 
region.  By  the  end  of  the  third  digestive  period,  these  clumps  of 
Trypanosomes  have  broken  through,  and  partly  block  up  the  lumen  ; 
and  in  the  next  biting  act  they  are  forcibly  ejected  into  the  blood  of  the 
owl.  Thus  the  parasites  cannot  leave  the  gnat  until  the  fourth  meal, 
including  that  which  effected  their  entry,  has  taken  place  ;  and  Schaudinn 
found  that  the  shortest  time  elapsing  between  entrance  and  exit  was  seven 
or  eight  days,  when  the  insects  were  maintained  at  the  optimum  tempera- 
ture for  digestion. 

An  interesting  discovery  is  the  occurrence  of  true  hereditary  infection. 
After  breaking  through  the  wall  of  the  colon,  a  few  of  the  Trypanosomes, 
usually  females,  instead  of  being  carried  forwards,  may  pass  to  the 
ovarian  follicles,  penetrate  into  the  young  eggs,  and  so  infect  a  succeeding 

According  to  Prowazek  (I.e.),  the  behaviour  of  Trypanosoma 
hwisi  in  Haematopmus  and  its  passage  through  the  louse  resembles 
in  the  main  the  account  above  summarised.  Such  differences  as 
there  are  stand  in  close  relation,  on  the  one  hand,  to  the  somewhat 
different  mode  of  feeding  and  of  absorption  of  nutriment  in  the 
louse,  and  on  the  other  hand  to  the  fact  that  T.  hwisi  appears  to 
be  more  resistant  to  "  external "  influences. 

With  regard  to  other  Mammalian  Trypanosomes,  the  evidence 
so  far  available  is  mostly  to  the  effect  that  they  are  confined  entirely 
to  the  alimentary  canal,  and  never  occur  in  other  organs  of  the 
insect.  Concerning  T.  gambiense  in  G.  palpalis,  Minchin,  Gray, 
and  Tulloch  (I.e.)  remark  that  these  parasites  were  found  only  in 
the  mid-gut,  and  never  passed  either  backwards  into  the  proctodaeum 
or  forwards  into  the  proventriculus.1  According  to  Stuhlmann  (I.e.), 
T.  brucii  is  apparently  much  more  at  home  in  G.  fusca  (which  may 
prove  to  be  its  true  specific  host),  being  met  with  in  different  forms 
from  the  hind-gut  (colon)  to  the  proboscis.  But  this  author  also 
emphasises  the  fact  that  the  Trypanosomes  were  never  observed 
anywhere  else,  and,  particularly,  never  in  the  salivary  glands.  The 
only  positive  observation  of  the  occurrence  of  Trypanosomes  in  the 
salivary  glands  which  need  be  taken  into  account  is  the  recent 
statement  made  by  Koch  (29)  that,  of  the  different  types  which 

1  Gray  and  Tulloch  (/.c.)  stated  that  they  had  observed  T.  gambiense  in  the 
salivary  glands,  but  Minchin  has  since  shown  that  what  they  took  to  be  salivary 
glands  was  in  reality  proventriculns  ;  moreover,  they  may  have  been  dealing,  not  with 
T.  gambiense,  but  with  one  of  the  other  parasites  in  this  fly. 


he  noticed  in  Glossinae  (sp.  not  given),  one  which  from  its  entire 
agreement  with  T.  gambiense  was  to  be  identified  with  that  form 
occurred  in  two  instances  in  the  salivary  glands.  If  this  observation 
be  corroborated,  its  importance  is,  of  course,  very  great. 

Several  important  facts  have  been  lately  brought  forward  by 
Brumpt  (10-12),  which  tend  to  show  that  the  habitat  of  Piscine 
Trypanosomes  in  leeches  is  also  restricted  to  the  alimentary  canal.1 
Three  types  of  behaviour  can  be  distinguished,  (a)  The  parasites 
develop  solely  in  the  stomach  and  never  pass  into  the  intestine  or 
into  the  sheath  of  the  proboscis.  At  the  moment  when  the  leech 
sucks  the  blood  of  another  fish,  the  Trypanosomes  pass  into  the 
latter  directly,  by  way  of  the  proboscis.  This  mode  is  exemplified 
by  T.  remaki  of  the  pike.  (/>)  The  development  begins  in  the 
stomach  and  is  continued  in  the  intestine,  where  the  parasites  may 
remain  for  a  long  while.  From  the  intestine  the  Trypanosomes 
pass  back  into  the  stomach,  to  gain  at  length  the  proboscis-sheath. 
T.  granulosum  of  the  eel  is  an  example  of  this  type.  In  the  third 
variety  (c)  the  development  goes  on  in  the  stomach,  but  the  para- 
sites succeed  in  passing  finally  into  the  proboscis -sheath;  ex.: 
T.  danilewskyi  of  the  carp.  In  the  case  of  certain  marine  forms 
(T.  raiae  and  T.  scyllii),  whose  development  goes  on  in  Pontobdella, 
Brumpt  found  the  parasites  in  the  stomach  and  intestine,  but  could 
not  ascertain  how  they  got  back  into  the  fish.  Miss  Robertson, 
however,  has  lately  described  (72)  various  developmental  phases 
of  a  Trypanosome  which  she  regards  as  identical  with  T.  raiae,  and 
states  that  small  slender  forms  do  migrate  up  into  the  proboscis  : 
it  is  probably  these  which  serve  to  infect  the  Vertebrate. 

2.  Relation  to  tlie  Vertebrate  Host. — Once  an  entrance  into  the 
blood  is  effected,  the  parasites  pass  rapidly  into  the  general  circula- 
tion, and  are  thus  carried  to  all  parts  of  the  body.  In  considering  the 
distribution  and  numerical  abundance  or  otherwise  of  the  Trypano- 
somes in  any  given  individual,  it  is  necessary  to  bear  in  mind 
whether  they  are  in  a  tolerant  host  or  in  an  unaccustomed  one. 
Dealing  with  the  former  case  first,  the  trend  of  observation  points 
to  their  being  usually  rather  scarce,  sometimes  very  rare.  The 
reason  for  this  scarcity  is  probably  the  fact  that  multiplicative 
phases  are  very  rarely  met  with,  at  all  events  in  the  general 
circulation.  Except  for  a  short  period  at  the  beginning  of  the 
infection,  multiplication  appears  to  be  largely  in  abeyance ;  this  has 
been  well  shown  by  Laveran  and  Mesnil  (37)  in  the  case  of  T. 
lewisi  of  the  rat.  The  parasites  are  often  more  numerous  in  the 
spleen,  bone-marrow,  kidneys,  and  liver  than  elsewhere ;  and  it  has 
been  found  that  multiplication  goes  on  rather  more  actively  in  the 
capillaries  of  these  organs.  One  very  important  point  may  be 

1  Brumpt  has  recently  noted  (14),  however,  cases  of  hereditary  infection  of  leeches, 
with  both  Trypanosoma  and  Trypanoplasma. 



conveniently  mentioned  here,  namely,  that  hereditary  infection  of  the 
Vertebrate  host  is  not  known  to  occur  in  the  case  of  most  of 
the  great  classes.  Moreover,  in  Mammals,  whether  tolerant  or 
unaccustomed  hosts,  the  parasites  appear  to  be,  as  a  general  rule, 
unable  to  traverse  the  (uninjured)  placenta.  Pricolo  has  recently 
stated,  however  (67),  that  he  has  found  T.  duttoni  in  the  foetus 
of  an  infected  mouse,  and  thinks  this  a  case  of  true  hereditary 

The  Trypanosomes  in  the  active,  motile  form  are  always  free  in 
the  blood-plasma  (intercorpuscular).  It  is  very  uncertain  whether 
the  parasites  ever  come  into  relation  with  the  blood -corpuscles. 
According  to  Schaudinn's  investigation  on  two  Avian  forms,  one, 
namely,  Trypanomorpha(Trypanosoina}noduae,  becomes  in  certain  phases 
attached  to  a  red  blood-corpuscle  (ectocorpuscular),  while  at  other 
times  it  penetrates  inside  the  corpuscle  (endocorpuscular)  and  eventu- 
ally destroys  it.  •  The  other  form,  Trypanosoma  (Spirochaeta}  ziemanni, 
apparently  draws  up  into  itself  the  white  corpuscle  (leucocyte)  to- 
which  it  becomes  attached.  It  must  be  admitted,  however,  that 
some  doubt  exists  as  to  these  alleged  occurrences.1  In  addition 
there  are  two  or  three  very  positive  statements  of  observations 
showing  that  other  Trypanosomes,  including  Mammalian  forms, 
may  come  into  relation  with  the  red  corpuscles ;  see  BufFard  and 
Schneider  (16)  with  regard  to  T.  equiperdum,  and  Voges  (85)  with 
regard  to  T.  equinum.  On  the  other  hand,  Prowazek  (68)  could 
find  neither  an  ecto-  nor  an  endocorpuscular  condition  in  T.  lemsi, 
and  considers  that  the  habitat  of  this  parasite  is  restricted  to 
the  plasma. 

Considering  now  the  Trypano- 
somes in  an  unaccustomed  Mam- 
malian host,  for  which  they  are 
lethal,  the  parasites  may  either 
remain  infrequent  or  rare  —  some- 
times, indeed,  being  unnoticed  until 
shortly  before  death — or  they  may 
soon  become  numerous  and  go  on 
increasing  (Fig.  5).  In  the  latter 
case  the  disease  is  acute  and  rapidly 
fatal ;  in  the  former  it  is  more  chronic 

and  lasts  much  longer,  often  several  gjg^  °«!  Wit* ;   b, 

There  is  often  considerable  varia- 
bility with  regard  to  the  appearance  and  number  of  the  parasites  in 

1  It  is  said  that  Schaudinu  has  mistaken  two  distinct  Haemosporidian  parasites, 
a  Hcdteridium  and  a  Leucocytozoon,  for  resting-phases  of  these  otber  Haematozoa  (see 
under  "  Life-Cycle  "). 

FIG.  5. 

Trypanosoma  i'/n/y>r/v/ii;/)  (of  Dourine), 
eight  days  after 
ites ;    b,    blood- 
corpuscles.    (After  Doflein.) 


the  blood  at  any  moment.  Occasionally  and  at  irregular  intervals, 
evidently  following  upon  a  period  of  multiplication,  the  Trypano- 
somes  may  be  fairly  numerous,  their  appearance  frequently  coinciding 
with  an  access  of  fever.  At  other  times,  they  seem  to  vanish  almost 
entirely  from  the  peripheral  circulation ;  for  what  reason,  however, 
is  not  certain.  Some  authorities  attribute  it  to  the  rise  in  tempera- 
ture, as  being  unfavourable  to  the  parasites ;  others  think  it  is 
due  to  the  more  potent  operation  of  chemical  and  physiological 
defensive  agencies  of  the  host  at  a  higher  temperature.  However 
this  may  be,  it  has  long  been  known  that  certain  of  the  organisms 
situated,  probably,  in  some  internal,  more  favourable  part  of  the 
body  can  survive  and  give  rise  later  to  a  fresh  succession  of 
parasites  in  the  blood.1 

The  main  features  of  the  illness  show  a  general  agreement, 
whichever  variety  of  trypanosomosis  is  considered;  one  symptom 
may  be,  of  course,  more  marked  than  another  in  a  particular  type. 
The  pathogenic  effects  are  chiefly  referable  to  disorganisation  either 
of  the  circulatory  or  of  the  nervous  system,  or  of  both  combined. 

Fever  always  occurs,  at  some  time  or  other,  during  the  course  of  the 
malady.  Its  manifestation  is  extremely  irregular,  both  in  character  and 
in  time  of  occurrence,  and  it  is,  therefore,  usually  readily  distinguishable 
from  malarial  fever.  There  is,  particularly  in  chronic  cases,  marked  and 
progressive  anaemia  and  emaciation,  leading  to  pronounced  enfeeblement, 
which  is,  in  fact,  the  most  characteristic  symptom  of  naturally  occurring 
trypanosomosis.  A  common  feature  is  the  occurrence  of  oedematous 
swellings  in  various  parts,  chiefly  in  the  neighbourhood  of  the  genitals, 
of  the  abdomen,  and  around  the  eyes.  The  parasites  are  often  more 
numerous  in  the  bloody  serosities  bordering  these  places  than  in  the 
general  circulation.  This  fact  is  of  great  importance  in  connection  with 
the  transmission  of  Dourine.  In  this  disease  the  parasites  are  rare  in 
the  blood,  but  generally  numerous  in  the  immediate  neighbourhood  of 
the  oedematous  excoriations  on  the  penis,  so  that,  in  coitus,  they  come 
into  contact  with  the  vaginal  mucous  membrane  of  a  healthy  mare, 
through  which  they  are  able  to  pass. 

Nervous  symptoms  may  be  only  slightly  noticeable  (e.g.  a  dull  and 
lethargic  tendency  towards  the  close  of  the  illness),  or  they  may  be 
strongly  in  evidence,  especially  in  Dourine,  Mai  de  Caderas,  and  sleeping- 
sickness.  In  the  two  former,  more  or  less  general  paralysis  of  the 
posterior  part  of  the  body  frequently  sets  in  ;  Mai  de  Caderas  of  horses 
in  South  America  is,  indeed,  often  called  "  hip-paraplegia."  In  sleeping- 
sickness  the  Trypanosomes  penetrate  into  the  cerebro-spinal  canal,  and 
.can  usually  be  found  upon  centrifugalising  a  sufficient  quantity  of  the 

1  Holmes  (Journ.  Goinp.  Pathol.  xvii.,  1904)  and,  more  recently,  Salvin-Moore  and 
Breiiil  (Ann.  Trap.  Med.  i.,  1907)  consider  that  these  resistant  forms,  for  which  the 
latter  propose  the  term  "latent  bodies,"  are  represented  by  certain  of  the  amoeboid 
involution-forms  described  by  Bradford  and  Plimmer,  Laveran  and  Mesnil,  and 
others  (cf.  p.  222). 



fluid;  they  have  also  been  seen,  in  post-mortem  examination,  in  the 
lateral  ventricles  of  the  brain.  It  is  this  invasion  by  the  parasites  of 
the  nervous  system  that  marks  the  transition  of  the  case  from  one  of 
"  Trypanosoma-faveT "  (while  the  parasites  are  confined  to  the  blood)  to 
one  of  sleeping-sickness.  The  results  of  the  change  are  soon  apparent 
in  the  onset  of  lassitude,  tremor,  and  the  other  associated  nervous 
symptoms  which  characterise  this  dreadful  malady. 

Death  from  trypanosomosis  is  due  either  to  weakness  and  emaciation 
(in  chronic  cases),  or  to  blocking  of  the  cerebral  capillaries  by  the  parasites 
(where  these  are  abundant  and  the  disease  consequently  acute  and  rapid), 
or  to  the  disorganisation  of  the  nervous  system  (paraplegic  and  sleeping- 
sickness  forms).  Laveran  and  Mesnil  have  expressed  the  opinion  that 
some  factor  in  addition  to  the  presence  of  the  parasites  themselves — 
especially  when  these  are  rare — is  requisite  to  explain  the  severe  effects 
produced,  and  suggest  that  the  Trypanosomes  secrete  a  toxine.  Neither 
they  nor  other  investigators  have,  so  far,  been  able  to  discover  traces  of 
any  such  substance.  In  post-mortem  examination,  the  most  obvious 
pathological  feature  is  hypertrophy  of  the  spleen,  which  may  be  very 
pronounced.  The  lymphatic  glands  in  the  neck,  inguinal  region,  etc., 
are  often  greatly  swollen  and  contain  numerous  parasites. 

The  spleen  and  lymphatic  glands  are  undoubtedly  the  organs 
which  react  most  strongly 
to  the  parasites,  and  their 
enlarged  condition  is,  prob- 
ably, to  a  great  extent 
due  to  enhanced  activity 
in  elaborating  blood -cor- 
puscles and  leucocytes  to 
cope  with  the  enemy.  In- 
gestion  and  dissolution  of 
the  Trypanosomes  by 
phagocytes  has  frequently 
been  observed  (Fig.  6). 
It  is  very  likely  also  that 
the  haematopoetic  organs 
eecrete  some  chemical  or 
physiological  substance 
which  exerts  a  harmful 
action  on  the  parasites, 
causing  them  to  undergo 
involution  and  assume 
weird-looking  "amoeboid"  and  "plasmodial"  forms. 

In  A  the  leucocyte  is 

Fie.  6. 

Phagocytosis  of  T.  lewisi. 

beginning  to  engulf  the  Trypanosome  ;  in  B  the  latter 
is  completely  intracellular  ;  C-E  show  the  gradual  dis- 
solution of  the  parasite  (p).  n,  nucleus  of  leucocyte  ; 
c,  ingested  blood  -  corpuscles  ;  v,  vacuoles  remaining 
after  their  dissolution.  (After  Lav.  and  Mesn.) 


Trypanosomes  vary  greatly  with  regard  to  size ;  even  in  one 
and  the  same  species  this  variation  is  often  noticeable,  especially 



under  different  conditions  of  life.  The  well-known  Trypanosoma 
rotatorium  of  frogs  (Fig.  8,  A  and  B)  is,  taking  it  all  in  all,  one  of  the 
largest  forms  so  far  described.  Its  length1  varies  from  40  to  60  //, 
while  its  greatest  width  dorso-ventrally  -  is  from  8  to  30  ^  ;  in  the 



FIG.  7. 

Representative  Mammalian,  Avian,  and  Reptilian  Trypanosomes.  A,  Trypanosoma  lewisi, 
after  Bradf.  and  Plim.  ;  B,  T.  brucii,  after  Lav.  and  Mesn.,  x  2000 ;  C,  T.  gambiense  (blood,  T.- 
fever),  after  Bruce  and  Nabarro ;  D,  T.  equinum,  after  L.  and  M.,  x  2000;  B,  Trt/panomorpha 
(Trypanosoma)  noctuae,  after  Schaud.  ;  F,  Trypanosoma  avium,  after  L.  and  M.  ;  G,  T.  hannae, 
after  Hanna;  H,  T.  (Spirochaeta)  ziemanni,  after  Schaud.  ;  J,  T.  damoniae,  after  L.  and  M., 
x  2000.  c.g,  chromatoid  grains  ;  v,  vacuole  ;  l.s,  longitudinal  striation. 

very  wide  individuals  breadth  is  gained  more  or  less  at  the  expense 
of  length.  Conversely,  the  human  parasite,  T.  gambiense  (Fig.  7,  c), 
is  one  of  the  smallest  forms,  its  average  size  being  about  21 
to  23  ju,  by  1 1  to  2  p..  The  majority  of  Mammalian  Trypanosomes 

1  The  length  is  always  inclusive  of  the  flagellum,  unless  otherwise  stated. 

2  Adopting  Leger's  convention,  by  which  the  convex  side,  bearing  the  undulating 
membrane,  is  distinguished  as  dorsal ;  the  measurements  of  width  always  include  the 
undulating  membrane. 


are  fairly  uniform  in  size  (Fig.  7,  A-D),  the  chief  exceptions  being 
T.  theileri  (Fig.  33),  which  is  much  larger  than  the  rest,  varying 
from  30  to  65  p  in  length ;  and  T.  nanum,  which  is  correspondingly 
minute,  being  only  about  14  /A  long.  The  Piscine  forms,  on  the 
other  hand,  though  possessing  an  equally  great  range,  exhibit  a 
more  regular  gradation.  Starting  with  relatively  small  types,  like 
T.  remaki,  var.  parva,  with  a  medium  length  of  30  /x,  parasites  of  all 
sizes  are  to  be  met  with  up  to  T.  granulosum  (Fig.  8,  K)  and  T.  raiae 
(Fig.  38,  B),  which  are  among  the  longest  Trypanosomes  known, 
attaining  a  length  of  80  //. 

There  is  equally  great  diversity  of  appearance.  Typically  the 
body  is  elongated  and  spindle-shaped ;  it  is  generally  more  or  less 
curved  or  falciform,  and  tends  to  be  slightly  compressed  laterally. 
It  may  be,  however,  anything  from  extremely  slender  or  vermiform 
(Figs.  8,  K;  34)  to  thick-set  and  stumpy  (Figs.  8,  A;  35).  More- 
over, apart  from  the  fact  that  a  full-grown  adult,  ready  to  divide, 
is  in  many  cases  much  broader  than  a  young  adult  (cf.  T.  lewisi, 
Fig.  20,  B),  considerable  polymorphism  also  sometimes  occurs  (e.g. 
T.  rotatorium,  Figs.  8,  A,  B;  37).  Again,  there  can  be  little  or  no 
doubt  that,  in  some  instances  at  any  rate,  sexual  differentiation  is 
expressed  by  more  or  less  pronounced  differences  in  appearance. 
In  fact,  from  one  reason  and  another,  it  is  often  practically  impos- 
sible to  define  any  one  type  within  hard  and  fast  limits,  either  of 
shape  or  size. 

In  the  biflagellate,  Heteromastigine  forms  (Trypanoplasma  and 
Trypanophis),  the  anterior  extremity  of  the  body  is  that,  of  course, 
from  which  spring  the  two  flagella.  With  regard,  however,  to  the 
correct  orientation  in  the  uniflagellate  Trypanosomes  (the  genus 
Tri/panosoma  sens,  lat.)  considerable  uncertainty  exists.  For  the 
present,1  in  order  to  avoid  confusion,  the  two  ends  may  be  desig- 
nated as  flagellate  or  flagellar,  and  non-flagellate  or  aflagellar 
respectively.  On  the  whole,  the  flagellar  extremity  is  fairly 
uniform  and  nearly  always  more  or  less  tapering;  but  the  non- 
flagellate  end  presents  great  variation,  being,  as  Laveran  and 
Mesnil  point  out,  particularly  plastic.  On  the  one  hand,  it  may 
be  blunt  and  even  rounded  off  at  the  tip,  as  in  certain  individuals 
of  T.  brucii  (Fig.  7,  B),  T.  equiperdum  (Fig.  32,  D),  and  in  a  Trypano- 
some  of  Senegambian  birds  (Fig.  35) ;  on  the  other  hand,  it  may 
be  very  long  and  attenuated,  as  in  T.  Jiannae  (Fig.  7,  G),  occasionally 
simulating  a  true  flagellum  to  a  remarkable  degree,  this  being  the 
case  in  T.  polyplectri.  Between  these  two  extremes  all  manner  of 
intermediate  conditions  are  to  be  found.  An  instance  which  well 
illustrates  the  great  variability  in  one  and  the  same  form  is  seen  in 

1  The  whole  question  is  so  closely  bound  up  with  that  of  the  phylogeny  of  the 
group  that  its  consideration  is  best  deferred  until  the  two  can  be  discussed  together 
(see  below,  p.  246). 



Fio.  8. 

Representative  Amphibian  and  Piscine  Trypanosomes.    A  and  B,  Trypanosoma  rotatorium, 
after  Lav.  and  Mesn.,  x  1400;  C,  T.  inopinatum,  after  Sergent,  x  1000;  D,  T.  karyozeukton, 

after  L.  and  M.,  x  2000.  h,  clear  zone  or  halo  around  kinetonucleus  ;  eh,  chain  of  chromatic 
rodlets  running  between  the  two  nuclei ;  a.fl,  anterior  flagellum  ;  p.fl,  posterior  flagellum  ;  l.s, 
longitudinal  striations  or  myonemes  ;  v,  cytoplasmic  vacuole. 

T.  lewisi.  Usually  this  parasite  has  a  shai-p,  pointed  aflagellar  end 
(Fig.  7,  A)  ;  but  in  many  of  the  individuals  found  in  rats  which 


have  been  recently  infected  (e.g.  five  or  six  days  previously)  this 
extremity  is  enormously  drawn  out  and  tapering  like  a  whip  (Fig. 
9).  In  such  forms  the  flagellum  is  often  very  short. 

The  two  flagella,  in  Trypanoplasma  and  Trypanophis,  are  inserted 
into  the  body  close  to  the  anterior  end  (Fig.  8,  F,  G).  They  are 
quite  separate  from  each  other,  and  while  one  (that  most  anteriorly 
situated)  is  entirely  free  and  directed  forwards,  the  other  at  once 
turns  backwards  and  is  attached  to  the  convex  (dorsal)  side  of  the 
body  for  the  greater  part  of  its  length.  This  latter  flagellum 
terminates  in  a  shorter  or  longer  free  portion. 

The  comparative  degree  of  development  of  the  two  flagella  in 
different  cases  is  worth  pointing  out,  since  it  is  very  instructive  in 
a  phylogenetic  connection.  Starting  with  Bodo  lacertae,  from  a 
type  similar  to  which  the  biflagellate  forms  may  be  derived,  both 
flagella  are  of  about  equal  total  length,  and  the  trailing  one  does 
not  reach  the  posterior  limit  of  the  body.  In  Trypanophis  grobbeni 
(Fig.  30)  the  posterior  flagellum  is  more  developed  than  the 
anterior  one,  and  attached  to  the  side  of  the  body,  but  its  free 
termination  is  very  short.  In  Trypano- 
plasma  borreli  the  anterior  flagellum  and 
the  free  portion  of  the  posterior  one  are 
of  equal  length.  Lastly,  in  T.  cyprini 
the  former  is  much  shorter  than  the 
latter,  and  shows  signs  of  reduction. 
From  this  condition  to  its  disappearance 
is  but  a  small  step. 

In  all  other  Trypanosomes  there  is 
only  one  flagellum,  which  is  invariably 
attached  to  the  body  in  the  same  manner 
as  the  posterior  one  of  the  biflagellate 
forms.  The  point  of  origin  of  the 
flagellum  is  generally  near  the  non- 
flagellate  end,  but  may  vary  consider- 
ably. Although  there  is  usually  a  free 
continuation  of  the  flagellum,  it  may  be 
short  or  lacking  (cf.  Fig.  34). 

Along  the  dorsal  side  runs  a  char- 
acteristic fin-like  expansion  of  the  body,  the  undulating  membrane 
This  always  begins  proximally  at  the  place  where  the  attached 
flagellum  emerges  from  the  body ;  and  its  free  edge  is  really  con- 
stituted by  the  latter,  which  forms  a  flagellar  border,  more  or  less 
sinuous  in  outline.  The  membrane  may  be  only  narrow,  and 
chiefly  discernible  by  its  well-marked  border  (Figs.  7,  A,  G ;  8,  c), 
or  it  may  be  well  developed  and  sometimes  thrown  into  broad  folds 
or  pleats  (Figs.  7,  r ;  8,  A,  B).  Distally  the  membrane  thins  away 
.concurrently  with  the  body. 

T.  lewisi,  from  a 
rat  five  days  after 
inoculation  to  show 
the  remarkably  long 
aflagellarend.  (From 
an  original  drawing 
kindly  lent  by  Dr. 
J.  D.  Thomson.) 


Minute  Structure. — The  body  appears  to  lack  any  distinct 
limiting  membrane  or1  cuticle.  A  differentiation  of  the  peripheral 
cytoplasm  in  the  form  of  an  ectoplasmic  layer,  the  so-called  "  peri- 
plast,"  has  only  been  definitely  described  in  a  few  cases  (Prowazek 
[68],  Wasielewsky  and  Senn  [86]).  Nevertheless,  it  is  probable 
that  in  most  Trypanosomes  there  is  such  a  layer,  although  it  may 
be,  in  some  forms,  only  poorly  developed  around  the  body  generally. 
The  undulating  membrane,  however,  is  certainly  largely,  if  not 
entirely  an  ectoplasmic  development.  This  is  usually  much  clearer 
and  more  hyaline  in  appearance  than  the  general  cytoplasm.  The 
latter  is  finely  granular  or  alveolar  in  character,  though  its  exact 
degree  of  coarseness  and  density  varies  in  different  forms,  some- 
times even  in  different  parts  of  the  same  individual.  The  cyto- 
plasm of  male  forms  is  in  general  clearer  and  less  granular  than 
that  of  female  ones.  The  cytoplasm  in  T.  mega  and  T.  karyozeiitton 
is  rather  unusual  in  structure.  In  the  third  of  the  body  on  the 
aflagellar  side  of  the  nucleus,  it  is  very  loose  and  spongy ;  in  the 
other  two -thirds,  it  is  arranged  in  alternating  light  and  dark, 
densely-staining  bands  ("  hyaloplasm  "  and  "  spongioplasm  "),  run- 
ning more  or  less  longitudinally. 

Cytoplasmic  inclusions  of  one  kind  or  another  are  often  to  be 
found.  In  many  Trypanosomes,  deeply -staining  granules  occur, 
which  vary  greatly  in  number  and  size.  These  granules  appear 
to  be  chiefly  distributed,  as  a  rule,  in  the  flagellate  half  of  the 
body  (Fig.  7,  B,  D).  They  are  of  a  chromatoid  nature,  and  probably 
derived  from  the  nucleus  (see  Lignieres  [54]).  In  Trypanophis  there 
are  one  or  two  rows  of  highly  refractive,  yellowish  inclusions  run- 
ning the  length  of  the  body  (Fig.  30).  It  is  thought  that  these 
represent  collections  of  fatty  or  oily  substances.  In  certain  forms, 
a  well-defined,  usually  oval  vacuole  is  often,  though  not  constantly 
present,  situated  at  a  varying  distance  from  the  aflagellar  end  (Figs. 
7,  C,  G ;  8,  F).  There  is  no  reason  to  doubt  that  this  vacuole  is  a 
normal  cell-constituent,  for  it  has  been  observed  in  parasites  in  their 
natural  (tolerant)  hosts  under  quite  normal  conditions. 

Until  recently,  very  little  was  known  with  regard  to  the 
details  of  nuclear  structure.  A  Trypanosome  was  merely  described 
as  possessing  an  unmistakable  nucleus,  and  also  a  small  deeply- 
staining  element  of  uncertain  significance,  situated  at  the  root  of 
the  flagellum,  and  termed  variously  "  blepharoplast,"  centrosome, 
or  micronucleus.  It  is  to  Schaudinn  that  we  are  indebted  for  the 
revelation  of  the  essential  nuclear  nature  of  the  latter  organella, 
its  intimate  connection  with  the  larger  nucleus  and  the  complexity 
and  differentiation  which  the  whole  nuclear  apparatus  may 
exhibit.  Since  then  several  workers  have  brought  forward 
observations  relating  to  one  point  or  another,  which,  taken  alto- 
gether, suggest  strongly  that  the  nuclear  organisation  of  Trypano- 



somes  in  general  is  based  upon  a  plan  fundamentally  similar  to 
that  described  by  Schaudinn  in  the  case  of  his  Avian  parasite, 
Trypanomorpha  noduae.  The  development  and  ultimate  constitution 
of  the  nuclear  apparatus  in  this  type  are  as  follows  : — 

The  account  may  be  commenced  with  the  condition  found  in  an 
indifferent  ookinete  or  individual  which  will  become  an  indifferent  (non- 
sexual)  Trypanosome.  Here  a  single,  large  compound  or  double  nucleus 
is  present,  consisting  of  an  external  portion  and  of  rtn  internal,  central 

FIG.  10. 

Development  of  an  indifferent  Try- 
panosome from  an  ookinete  of  indif- 
ferent character.  (After  Schaudinn.) 
t.chr,  trophonuclear  chromosome ; 
K.chr,  kinetonuclear  chromosome  ;  c, 
centrosomic  granule ;  a.s,  first  axial 
spindle  ;  o.s2,  a.s  3,  second  and  third 
spindle  ;  t.  trophonucleus  ;  k,  kineto- 
nucleus ;  fc.e,  kinetonuclear  centro- 
soine;  t.f,  trophonuclear centrosome ; 
m,  myonemes  ;  /.';,  flagelliir  border  of 
undulating  membrane  (third  axial 
spindle) ;  u3,  its  proximal  centrosome. 

portion  (Fig.  10,  A).  The  former  has  eight  distinct,  peripherally  situated 
chromosomes ;  the  latter  also  has  eight  separate  chromosomes.  In  the 
centre  of  all  is  a  well-marked  centrosomic  granule  (c).  The  first  change 
takes  place  by  the  inner  body  becoming  amoeboid  and  giving  up  its 
material  to  the  outer,  surrounding  part  (B).  The  result  is  that  the  eight 
chromatic  elements  of  the  former  become  united,  by  the  aid  of  the  plasti- 
noid  basis  present,  with  those  of  the  latter,  leaving  the  above-mentioned 
grain  in  the  middle.  This  granule  divides  in  a  dumb-bell-like  manner, 
producing  a  small  axial  spindle  (c,  a.s.),  around  which  the  eight  compound 
chromosomes  arrange  themselves.  These  next  split,  and  the  halves  pass 
to  either  end,  forming  a  diaster  which  is  markedly  heteropolar.  The 


right  (or  dorsal)  half  is  perceptibly  smaller,  but  denser  and  more  deeply 
staining  than  the  other.  In  this  manner,  therefore,  two  distinct  nuclear 
bodies  are  formed,  of  different  size  and  character.  They  remain  connected 
together  by  a  fine  achromatic  thread,  representing  the  original  central 
spindle,  which  ends  in  a  small  granule  near  the  centre  of  each.  The 
larger  nucleus,  lying  nearer  the  middle  of  the  body,  rapidly  reconstitutes 
itself  and  enters  upon  a  resting-phase.  This  nucleus  regulates  the  trophic 
functions  of  the  cell,  for  which  reason  we  have  proposed  (3)  for  it  the 
name  trophonucleus. 

Meanwhile,  the  other,  smaller  nucleus  proceeds  to  give  rise  to  the 
characteristic  locomotor  apparatus  of  the  Trypanosome.  It  passes  forwards 
slightly  and  takes  up  a  position  at  the  periphery  of  the  endoplasm,  lying 
indeed  against  the  limiting  ectoplasm.  Its  centrosome  divides  again  in 
a  similar  manner,  forming  another  axial  spindle  (E,  a.s  2)  at  right  angles, 
as  before,  to  the  length  of  the  parasite.  Another  heteropolar  division 
next  takes  place,  giving  rise  to  two  daughter-nuclei ;  these  also  remain 
connected  together  by  the  drawn-out  central  spindle,  which  join  the  two 
centrosomic  granules.  The  peripheral  daughter-nucleus,  situated  almost 
in  the  ectoplasm,  forms  yet  another  spindle  (F,  a.s3),  whose  axis  is  now, 
however,  longitudinal.  This  assumes  large  proportions  and  spreads 
forward  to  the  anterior  end  of  the  body,  the  whole  lying  in  the  ectoplasm, 
which  becomes  greatly  developed  to  form  the  undulating  membrane. 
The  central  spindle  becomes  excentric  in  position  and  sinuous  in  outline, 
and  strengthens,  or  rather  itself  constitutes,  the  free  edge  of  the  membrane, 
forming  a  -flagellar  border  to  it  (H,  /.&).  A  supporting  framework  is 
formed  by  eight  myonemes,  representing  the  eight  elongated  daughter- 
chromosomes,  four  of  which  are  arranged  on  each  lateral  surface.  The 
flagellar  spindle  does  not  stop  on  reaching  the  anterior  end  of  the  body, 
but  continues  to  elongate,  drawing  out  with  it  the  undulating  membrane, 
which  narrows  and  finally  thins  away.  The  myonemes  then  unite  with 
the  spindle  to  form  the  free  flagellum,  the  centrosome  at  the  distal  end 
disappearing  as  such,  but  that  at  the  basal  or  proximal  end  persisting  (c). 
By  this  time  the  other  daughter-nucleus  has  become  rounded  off  as  the 
kinetonucleus  (k),  which  regulates  all  the  kinetic  activities  of  the  parasite  ; 
it  remains  connected  with  the  locomotor  apparatus  by  a  delicate  thread, 
representing  the  second  axial  spindle.1 

According  to  Prowazek's  recent  investigations,  the  same  type  of 
nuclear  structure  is  also  shown  by  two  Mammalian  forms,  T.  lewisi 
and  T.  brucii ;  indeed,  it  is  maintained  that  the  system  of  axial 
spindles  produced  by  successive  divisions  of  the  karyocentrosome 

1  Two  other  points  bearing  on  the  view  that  the  flagellum  represents  the  greatly 
elongated  axial  spindle  of  a  nuclear  division  may  be  noted.  In  Trypanosoma 
johnstoni,  where  there  is  no  free  portion  of  the  flagellum,  this  terminates  (at  the 
limit  of  the  cytoplasm)  in  a  small  deeply-staining  granule  (Fig.  34),  perhaps  com- 
parable to  the  distal  centrosome  of  such  a  spindle.  Again,  Miss  Robertson  (72) 
sums  up  her  account  of  the  origin  of  the  flagella  in  the  development  of  the  flagellate 
form  from  the  rounded,  aflagellar  type  in  the  case  of  her  leech -Trypanosome  by 
saying,  "the  two  flagella  appear  to  be  developed  from  a  pair  of  arrested  mitotic 
figures  developed  out  of  the  distal  of  the  two  segments  into  which  the  original 
kinetonucleus  divides." 



is  even  more  elaborate  in  the  former  parasite  than  in  the  case  just 
described.  Further  evidence  in  support  of  Schaudinn's  view  of 
the  intimate  relation  and  correspondence  between  the  two  nuclear 
organellae  is  furnished  by  L6ger  (50),  who  has  observed,  in 
"ookinetes"  of  T.  barbatiilae  (see  under  "Life-Cycle"),  heteropolar 
division  of  a  single  large  nucleus,  doubtless  leading  to  the  forma- 
tion of  tropho-  and  kinetonucleus ;  and  by  Bradford  and  Plimmer 
(6),  who  have  observed  the  latter  element  ("  micronucleus  ") a  given 
off  from  the  larger  nucleus  in  T.  brucii.  Perhaps  the  most  striking 
confirmation  of  the  essential  nuclear  character  of  the  kinetonucleus 
is  afforded,  however,  by  a  comparison  of  this  organ ella  in  Trypano- 
plasma  borreli,  where  it  is  particularly  large,  and  like  a  nucleus ;  in 
fact,  it  was  originally  regarded  as  the  nucleus  (trophonucleus)  of 

FIG.  11. 

Trypanoplauma  lorreli,  Lav.  and  Mesn.  a.f,  anterior  flagellum  ;  p.f,  posterior  flagellum  ;  m, 
undulating  membrane  ;  T,  trophonucleus  ;  K,  kinetonucleus  ;'  /,  fibril  (myoneme) ;  c,  centre- 
somic  granule  at  base  of  flagellum.  (After  Leger.) 

this  parasite.  Moreover,  in  addition  to  the  kinetonucleus,  and 
immediately  in  front  of  it,  two  centrosomic  granules  can  be 
distinctly  seen,  one  at  the  base  of  each  flagellum  (shown  clearly  in 
Lager's  figures,  Fig.  11,  B,  c).  In  Tnjpaiwsoma  also,  in  many  cases, 
the  root  of  the  flagellum  is  not  actually  connected  with  the  kineto- 
nucleus, but  terminates  before  reaching  it  in  an  unmistakable 
granule,  which  we  have  found  to  stain  much  darker  than  the 
flagellum.  Lastly,  in  this  connection  the  writer  has  been  very  kindly 
permitted  by  Prof.  Minchin  to  make  use  of  two  figures  of  his  (about 
to  be  published)  of  Trypanosoma  grayi  undergoing  division,  in  which 
centrosomic  granules,  associated  with  the  kinetonuclei,  are  clearly 

1  It  is  necessary  to  point  out  that  the  kinetonucleus  is  not  a  "micronucleus," 
in  the  sense  in  which  this  term  is  always  used  as  applying  to  that  body  in  the 
Tnfusoria.  In  the  Trypanosomes  both  nuclei  are  equally  essential  and  functional, 
in  somatic  life  as  well  as  in  sexual  reproduction. 


shown  (Fig.  12).  An  additional  feature  of  interest  is  the  presence 
of  a  well-developed  axial  spindle,  still  connecting  the  two  tropho- 
nuclei  (which  have  divided  last),  and  ending  in  a  granule  inside 
each,  which  is  doubtless  the  trophonuclear  centrosome.  In  other 
cases  (e.g.  T.  remaki,  Trypanoplasma  borreli,  Trypanopliis)  as  well,  a 
large,  distinct  granule  has  been  described  in  the  centre  of  the  nucleus, 
which  very  probably  represents  the  trophonuclear  centrosome 
(karyocentrosome).  To  sum  up,  the  above  facts  leave  little  reason  to 
doubt  (a)  that  the  kinetonucleus  of  a  Trypanosome  is  not  merely 
an  extranuclear  centrosome,1  but  a  true  nucleus,  homologous  with 
and  equivalent  to  the  trophonucleus,  the  two  being  specialised  for 
different  functions  ;  and  (b),  that  distinct  centrosomes  are  associated 
with  both  nuclei,  the  trophonucleus  possess- 
ing an  intranuclear  one,  while  in  connection 
with  the  kinetonucleus  there  is  an  extra- 
nuclear  one  (at  the  base  of  the  flagellum) 
and  perhaps  also  an  intranuclear  one  (accord- 
ing to  Schaudinn). 

Both    nuclei   vary  greatly  with    regard 
to  their  position  in  the  body,  in  different 
forms,   as   will  be   seen   on   comparing  the 
figures  given.     As  a  rule,  the  trophonucleus 
PIG.  12.  lies  somewhere  near  the  middle  of  the  body, 

Trypanosorna  grayi,  dividing,  and  the  kinetonucleus  near  the  aflagellar 
nlnTdrlwtfti  So^SS  end,  being  farther  from  it  in  proportion  as 
somic  granules  are  seen  one  the  extremity  is  tapering.  In  some  cases, 

above  each  kinetonucleus.  '  a.  .  .       ' 

however,  at  all  events  during  certain  periods 

of  life,  the  two  nuclei  lie  close  together  centrally,  at  times  being 
actually  in  contact  (cf.  T.  inopinatum,  Fig.  8,  C ;  T.  "  iransvaaliense," 
Fig.  33 ;  T.  rotatorium,  Fig.  8,  B;  and  T.  lewisi,  young  forms,  Fig. 
21,  E).  The  trophonucleus  is  generally  ovoid  in  shape,  the  longer 
axis  being  longitudinal,  but  in  the  Trypanosome  described  by 
Button  and  Todd  from  Senegambian  birds,  and  also  in  T.  hannae, 
the  long  axis  is  transverse  to  that  of  the  body  (Figs.  7,  G;  35). 
As  regards  its  minute  structure,  the  trophonucleus  appears  generally 
to  consist  of  an  aggregation  of  chromatin  grains  embedded  in  a 
plastin-like  matrix.  No  mention  is  usually  made  of  a  nuclear 
membrane  or  reticulum.  In  his  account  of  Trypcmoplasma  borreli, 
it  may  be  noted,  Le"ger  (49)  has  described  eight  dumb-bell-shaped 
chromosomes.  An  unusual  appearance  of  the  trophonucleus  has 
been  observed  in  one  or  two  instances  (T.  brucii,  Stuhlmann  and 
Miss  Kobertson ;  T.  raiae,  in  the  leech,  Miss  Robertson).  In  these, 

1  Salvin-Moore  and  Breinl,  in  their  account  of  the  "  cytology  of  the  Trypanosomes  " 
(Ann.  Trap.  Med.,  Liverpool,  1907),  continue  so  to  regard  this  organella,  in  spite  of 
all  the  evidence  to  the  contrary,  much  of  which  (e.g.  that  furnished  by  Trypanoplasma) 
they  entirely  overlook. 


this  organella  is  very  much  elongated,  and  the  chrottiatin  is  arranged 
in  the  form  of  a  ladder  of  parallel  rods  or  pairs  of  granules  (chromo- 
somes ?).  There  is  not  much  to  note  with  regard  to  the  kineto- 
nucleus.  In  a  solitary  instance,  namely,  T.  equinum,  it  is  extremely 
minute  and  difficult  to  distinguish ;  it  appears  as  a  dot-like  thicken- 
ing at  the  root  of  the  flagellum  (Fig.  7,  r>).  In  this  case,  the 
organella  has  apparently  become  reduced. 

The  occurrence  of  prominent  myonemes  in  the  undulating 
membrane  of  Trypanomorpha,  and  their  nuclear  origin  (as  "  mantle- 
fibrils  "),  has  been  already  described.  According  to  Prowazek 
{I.e.),  a  similar  development  occurs  in  both  T.  lewisi  and  T.  brucii ; 
here  the  myonemes  lie  in  the  general  ectoplasm  of  the  body,  f oni- 
on each  side,  but  they  are  very  delicate  and  difficult  to  make  out. 
In  two  or  three  other  parasites  longitudinal  striations,  comparable 
to  muscle-fibrillae,  have  been  observed  ;  nothing  is  known,  how- 
ever, about  their  origin.  Thus  in  Trypanoplasma  borreli  there  are 
two,  one  on  each  side  of  the  body,  which  start  in  front  and  run 
backwards  more  than  half-way,  finally  joining  ventrally  (Fig.  11, 
•c,  /).  Again,  in  Trypanosoma,  soleae  (Fig.  8,  j),  the  ribbed  forms  of 
T.  rotatorium  (Fig.  37,  A),  and  in  T.  avium  (according  to  Novy  and 
M'Neal),  myoneme  striations  are  well  marked. 


A.  Movement. — In  general,  Trypanosomes  are  extremely  active 
.organisms.  According  to  the  manner  in  which  they  are  produced, 
two  kinds  of  movement  can  be  distinguished  :  (1)  displacement  of 
the  body,  usually  rapid  ;  and  (2)  creeping  and  pushing  movements, 
by  means  of  flexion,  extension  and  contraction  of  the  body,  etc. 
The  latter  kind  are  brought  about,  in  all  probability,  by  the  super- 
ficial myonemes  mentioned  above  ;  they  are,  in  fact,  often  comparable 
to  "  euglenoid  "  movements  (cf.  the  flexion  movements  of  sporozoites). 
In  all  such  cases,  it  is  important  to  note,  the  non-flagellate  end 
moves  first. 

In  active  movements  of  displacement,  the  flagellar  extremity 
generally  leads  the  way.  The  motion  may  be  very  rapid  and 
relatively  considerable,  as  in  T.  lewisi ;  or  sluggish  and  inconsider- 
able, as  in  T.  brucii,  whose  powers  of  active  displacement  appear 
slight  or  else  little  used.  There  is  some  difference  of  opinion  as 
to  whether  the  undulating  membrane  or  the  flagellum  plays  the 
principal  part  in  this  locomotion.  The  flagellum  doubtless  acts  to 
a  certain  extent  as  a  tractellum,  especially  in  cases  of  very  rapid 
movement.  In  Trypanoplasma,  in  which,  of  course,  the  anterior 
end  goes  first,  the  principal  organella  concerned,  according  to  Ledger 
(I.e.),  is  the  undulating  membrane,  whose  rapid  vibrations  produce 
.quickly  succeeding  waves,  running  backwards.  The  oscillations 


may  be  continued  into  the  posterior  flagellum,  which  then  acts  as  a 
pulsellum ;  Leger  thinks,  however,  that  this  flagellum  functions 
chiefly  as  a  rudder  (Schleppgeissel).  The  anterior  flagellum  is  not 
greatly,  if  at  all,  concerned  in  the  movement. 

All  Trypanosomes  undergo,  more  or  less  continually,  a  vibratile 
or  undulatory  motion  of  the  membrane,  which  may  take  place  in 
either  direction.  Among  the  elongated  Piscine  forms,  movements 
of  contortion  are  much  in  evidence,  the  body  being  frequently 
coiled  up  on  itself.  In  many  Trypanosomes,  again,  especially  the 
more  spirochaetiform  ones,  the  membrane  appears  spirally  wound 
round  the  body,  this  being  due  to  a  more  or  less  pronounced 
torsion  of  the  latter,  which  gives  the  animals  a  corkscrew-like  motion. 

B.  Agglomeration. — This  characteristic  phenomenon  of  Trypano- 
somes occurs  chiefly  or  only  upon  the  advent  of  unfavourable 
biological  conditions  in  the  surrounding  medium.  In  the  normal 
blood  or  other  humour  of  Vertebrate  hosts  agglomeration  has  only 
been  observed  in  one  or  two  cases,  when  it  has  been  termed  auto- 
agglomeration.  Agglomeration  is  readily  brought  about  artificially 
in  various  ways ;  e.g.  when  drawn  blood  containing  the  parasites  is- 
kept  for  some  time  at  a  low  temperature ;  when  sera  of  other 
animals,  especially  of  animals  which  have  been  once  or  twice  inocu- 
lated with  the  particular  Trypanosome,  are  added  to  fresh  blood ; 
or  by  the  addition  of  chemical  solutions.1 

Agglomeration  generally  commences  by  two  Trypanosomes 
coming  together  and  joining  (Fig.  14,  A) ;  and  the  union  may  some- 
times remain  only  binary.  In  most  cases,  however,  the  agglomera- 
tion progresses  rapidly,  a  number  of  parasites  collecting  round  a 
common  centre  and  forming  a  multiple  union  or  rosette  (Figs.  13  ; 
14,  B).  Such  a  cluster  or  rosette  is  known  as  a  primary  agglomera- 
tion, and  may  consist  of  as  many  as  a  hundred  individuals ;  some- 
times the  rosettes  themselves  become  grouped  together  to  form  large 
tangled  masses.  In  a  natural  (as  opposed  to  an  artificial)  mediumr 
agglomeration  of  a  particular  form  of  Trypanosome  takes  place, 
typically,  by  the  same  extremity.  In  Trypanomofpha  noctuae,  accord- 
ing to  Schaudinn,  this  is  the  flagellate  (anterior)  end ;  i.e.  the 
parasites  unite  with  the  flagella  pointing  towards  the  centre  (Fig.  1 3). 
In  Trypanosoma,  on  the  other  hand,  the  union  is  by  means  of  the 
aflagellar  end.2 

1  For  fuller  details  the  reader  is  referred  to  the  works  of  Laveran  and  Mesnil 
(37,  43),  Lignieres  (54),  Thiroux  (83),  and  others. 

2  In  artificial  cultures,  clusters  are  frequently  observed  in  which  the  arrangement 
of  the  parasites  is  not  constant,  even  in  the  same  species  ;  that  is  to  say,  some- 
times the  Trypanosomes  have  their  flagella  at  the  periphery,  while  at  others  the 
flagella  are  centrally  directed.     It  appears,  however,  that  two  entirely  different  pro- 
cesses are  concerned.     In  some  cases,  at  any  rate,  those  clusters  which  have  the 
flagella  pointing  centrally  are  instances  not  of  agglomeration,  but  of  rapid  successive 
division,  where  the  parasites  remain  more  or  less  in  contact  and  form  large  colonies. 
This  has  been  well  brought  out  by  Novy  and  M'Neal  (62,  63),  Thiroux,  and  others. 



This  peculiar  feature  of  Trypanosomes  differs  in  one  or  two 
important  respects  from  the  somewhat  similar  phenomenon  of 
agglutination  in  Bacteria.  The  Trypanosomes  do  not  in  the 
slightest  lose  their  mobility  during  the  process.  Each  individual 
continues  active  movements,  its  flagellum  lashing  away  at  the 
periphery,  and  appears  to  be  making  strenuous  endeavours  to  escape. 
Again,  a  rosette  is  able  to  become  disagglomerated ;  a  bacterial 
cluster  or  agglutination,  on  the  other  hand,  is  never  dissolved. 
Disagglomeration  is  appar- 
ently in  consequence  of  the 
retention  of  the  power  of 
movement  by  the  parasites. 
Sometimes  all  the  indi- 
viduals, apparently  quite 
unaltered  morphologically, 

FIG.  13. 

Agglomerated  cluster  of 
male  forms  of  Trypanomor- 
pha  noctuae  in  the  intestine 
of  the  gnat.  (After  Schau- 

FIG.  14. 

A,  binary  union  or  agglomeration  of  T. 
lewisi.  B,  primary  rosette  of  the  same  parasite. 
(After  L.  and  M.) 

become  thus  dispersed.  At  other  times  disagglomeration  is  only 
partial,  a  certain  number  of  the  more  feeble  Trypanosomes  remaining 
together  and  slowly  dying.  If  the  agglomerating  serum  is  very 
powerful,  however,  or  if  the  biological  conditions  remain  unfavour- 
able, the  rosette  does  not  break  up  and  the  parasites  at  length 
die  off. 

The  significance  of  the  process  has  yet  to  be  ascertained.  By 
some  it  is  regarded  as  a  purely  involuntary  proceeding  on  the  part 
of  the  parasites,  and  brought  about  more  or  less  mechanically.  A 
suggestion  put  forward  by  Lignieres  (54)  is  not  without  interest, 
particularly  when  the  recent  work  of  Calkins  on  the  essential 
meaning  of  fertilisation  is  borne  in  mind.  This  author  considers  it 
quite  probable  that,  as  a  result  of  the  close  intimacy,  a  molecular 
interchange  goes  on  between  the  associated  individuals,  which  may 
have  a  stimulating  or  recuperative  value. 

C.  Abnormal  and  Involution  Forms. — Involution  and  degenerative 
phases  of  Trypanosomes  have  received  attention  and  acquired  an 



importance  altogether  undeserved,  owing  chiefly  to  the  fact  that 
many  of  these  parasites  have  been  studied,  so  far,  only  in  strange 
and  unaccustomed  hosts — hosts  to  which  they  are  unadapted,  and 
for  which  they,  on  their  part,  prove  markedly  pathogenic. 

Trypanosomes  appear  to  be,  in  most  cases,  able  to  support,  for  a 
longer  or  shorter  period,  unfavourable  conditions  of  environment, 
whether  due  to  the  reaction  of  the  host  itself  or  to  the  transference 
of  the  parasites  to  a  strange  medium.  Sooner  or  later,  however, 
the  organisms  feel  the  effects  of  such  changed  circumstances  and 

Flo.  15. 

Involution  and  degeneration  forms  of  different  Trypanosomes.  A-E,  T.  gamble-use  (A,  C,  and 
B  after  Bruce  and  Nabarro ;  B  and  D  after  Castellani).  P,  K-P,  T.  brucii  (F  after  Br.  and 
PI.  ;  K-P  after  L.  and  M.).  G-J,  Q  and  R,  T.  equinum  (after  Lignieres.)  8,  T.  brucii,  plas- 
morlial  mass,  from  spleen  pulp  (after  Br.  and  PI.). 

become  markedly  altered.  The  strange  forms  and  appearances 
frequently  described  are  probably  for  the  most  part l  abnormal ;  i.e. 
they  do  not  represent  phases  in  the  typical  life-cycle,  but  are  vary- 
ing stages  in  a  process  of  degeneration.  Nevertheless,  it  by  no 
means  follows  that  the  parasites  rapidly  die  off.  On  the  contrary, 
many  of  these  involution-forms,  on  entering  the  blood  of  a  fresh 
host,  are  able  to  infect  it,  though  they  may  even  have  been  kept  for 
some  time  in  artificial  surroundings. 

The  course  which  involution  takes  varies  in  different  cases,  but 
the  process  generally  follows  one  or  another  of  three  lines,  which 

1  See  footnote  to  p.  222. 



may  occasionally  be  met  with  in  combination  in  any  given  abnormal 
form.  (a)  Chromatolysis.  Here  there  is  either  a  more  or  less 
complete  loss  by  the  nucleus  (usually  the  trophonucleus)  of  its 
chromatic  constituents,  which  pass  out  into  the  cytoplasm  leaving 
only  a  faintly  staining  plastinoid  basis  (Fig.  15,  A)  ;  or  else  direct 
fragmentation  of  the  nucleus  occurs  (F-j).1  (b)  Vacuolisation.  The 
frequent  presence  of  a  vacuole  in  many  Trypanosomes,  which  is 


FIG.  16. 

Involution  and  degeneration  forms  (continued).  A-C,  T.  bntcii,  after  Br.  and  PI.  ;  D-G,  T. 
iiomiiiense,  after  Castellani ;  H,  T,  briicii,  after  Martini ;  J,  K,  T.  equinum,  after  Voges  ;  L,  T. 
brucii,  agglomeration-cluster,  commencing  to  form  a  plasmodium,  after  I3r.  and  PI. 

probably  to  be  regarded  as  a  normal  cell-organella,  has  been  men- 
tioned above.  The  first  indication  of  abnormality  in  this  direction  is 
perhaps  afforded  when  the  vacuole  increases  very  greatly  in  size  (Figs. 

15,  E  ;  16,  E).     Other,  irregular  ones  may  appear  in  the  cytoplasm, 
when  the  involution  becomes  pronounced  in  character  (Figs.  15,  C; 

16,  G).     (c)  Change  of  form.     This  is,  from  the  weird  forms  often 
resulting,  the  most  obvious  line  of  involution.     Alteration  in  shape  is 
generally  accompanied  by  an  increasing  loss  of  mobility.     In  the 

1  In  certain  of  these  cases  it  is  possible  that  something  in  the  nature  of  chrom- 
idial  formation  may  be  going  on,  leading  to  nuclear  readjustment. 


case  of  single  forms  the  body  becomes  stumpy  (Fig.  15,  C-E),  losing 
almost  entirely  its  trypaniform  shape,  and  ends  by  being  ovoid  or 
like  a  ball  (c,  H,  L)  ; l  the  flagellum  is  limp  and  inactive  and  partially 
coiled  up  (j).  In  other  cases,  quite  irregular  multiplication  occurs, 
accompanied  by  incomplete  cytoplasmic  division,  leading  to  the  forma- 
tion of  distorted  multinucleate  and  multiflagellate  bodies  (Fig.  16, 
A— G).  Lastly,  various  fusion -forms  may  be  met  with,  masses  of 
Trypanosomes  gradually  losing  their  distinctness  and  constituting 
large  plasmodia  (Figs.  16,  L;  15,  s),  made  up  of  a  great  number  of 
nuclei  embedded  in  a  common  cytoplasmic  matrix. 

If  the  organisms  remain  subjected  to  the  unfavourable  influences, 
or  if  involution  has  reached  too  advanced  a  stage,  death  and  dis- 
integration result.  The  cytoplasm  is  the  first  to  disappear,  becoming 
hyaline  and  colourless,  and  refusing  to  stain  up.  The  nucleus 
rapidly  follows  suit.  The  most  resistant  elements  are  the  kineto- 
nucleus  and  flagellum,  which  may  persist  long  after  other  traces  of  the 
organism  have  vanished  (Fig.  15,  p),  the  former  as  a  little  thickening 
at  one  extremity  of  the  latter ;  sometimes  the  flagellum  alone  is  left. 


Binary  longitudinal  fission  is,  probably,  of  universal  occurrence, 
and  appears  to  be  the  usual  method  of  multiplication ;  though 
Trypanosoma  lemsi,  at  any  rate,  possesses  another  method  in 
addition,  namely,  rosette -like  segmentation. 

The  process  of  fission  begins  with  the  division  of  the  nuclear 
and  locomotor  apparatus,  but  the  actual  order  of  division  of  these 
different  organellae  appears  to  be  very  inconstant  and  variable. 
As  a  rule,  the  kinetonucleus  leads  the  way,  but  sometimes  the 
trophonucleus  may.  The  duplication  of  the  flagellum  begins  at 
its  proximal  end,  that  which  is  in  relation  with  the  kinetonucleus. 
Until  lately  the  process  has  always  been  considered  as  an  actual 
longitudinal  splitting  of  the  flagellum,  following  upon  the  separation 
of  the  two  daughter-kinetonuclei.  Now  and  again  examples  are 
met  with  in  which  the  duplication  of  the  flagella  has  taken  place 
before  the  kinetonucleus  has  divided.  It  seems  probable  that  it 
is  really  the  division  of  the  kinetonuclear  centrosome  which  is  the 
essential  prelude  to  the  division  of  the  locomotor  apparatus.  This 
flagellar  splitting  has  been  described  either  as  extending  to  the 
distal  end  of  the  undulating  membrane,  after  which  the  two  halves 
separate  (Fig.  17,  c),  or  as  being  practically  limited  to  the  root- 

1  It  is  here,  if  anywhere,  that  there  might  be  a  possibility  of  regarding  as  involution- 
forms  phases  which  really  belong  to  the  normal  life-cycle  ;  e.g.  rounded-off,  resting 
phases  (cf.  the  "  resistant  forms  "  of  Holmes  and  others).  In  such,  however,  the 
flagellum  would  doubtless  be  absent,  while  the  nuclear  elements  and  cytoplasm  would 
be  as  usual ;  in  fact,  the  parasites  might  well  show  a  resemblance  to  the  Leishman- 
Donovan  bodies  (cf.  pp.  255  et  seq.). 



portion,  which  becomes  thickened  and  then  divides,  one  half  break- 
ing away  as  a  new,  short  flagellum,  whose  further  growth  is  basal 
and  centrifugal  (Fig.  20,  D).  Schaudinn  found,  however,  that  in 

A.  C 

FIG.  17. 
Stages  in  binary  longitudinal  fission  of  T.  brucii.    (After  Lav.  and  Mesn.) 

Trypanomorphi  noctuae  the  whole  of  the  flagellum,  etc.,  is  developed 
quite  independently  from  the  daughter-kinetonucleus,  and  laid 
down  alongside  and  parallel  with  the  old  locomotor  apparatus ; 
moreover,  Prowazek  (I.e.)  and  also  M'Neal  (56)  maintain  that  the 
same  is  the  case  in  T.  lewisi.  Nevertheless,  in  many  cases  it  seems 
hardly  possible  to  doubt  that  there  is  actual  splitting  of  the 
flagellum ;  where,  for  in- 
stance, the  two  new  flagella 
of  the  proximal  part  of  the 
body  appear  to  actually 
join  arid  continue  as  one, 
yet  undivided  flagellum 
(as  seen  in  Fig.  17,  A 
and  B).  Again,  even 
where  a  daughter-flagellum 
is  separate  from  the  main 
one,  the  course  of  the  two 
is  often  so  exactly  parallel 
that  their  origin  by  longi- 
tudinal fission  is  highly 

So  far,  we  have  not  much  knowledge  with  regard  to  the 
cytological  details  of  nuclear  division.  Prowazek  has  given  a 
description  of  the  process  in  T.  brucii.  The  kinetonucleus  becomes 
thickened  and  spindle -like  (Fig.  18,  A).  Subsequently  it  becomes 

Flo.  18. 

Details  in  the  nuclear  division  of  T.  brucii. 
(After  Prowazek.) 



dumb -bell -shaped,  after  which  the  two  halves  become  farther 
separated,  remaining  connected  only  by  a  short  thread  (B). 
The  chromatin  of  the  trophonucleus  is  arranged  in  eight  rather 
elongated  chromosomes,  which  next  begin  to  divide  in  a  similar 
dumb-bell-like  manner  (Fig.  18,  c).  The  trophonuclear  karyosome 
(karyocentrosome)  has  frequently  divided  by  this  time ;  but  in 
one  instance  Prowazek  observed  it  much  drawn  out  and  functioning 
as  an  intranuclear  division  centre  (n),  the  chromatin  having 
become  aggregated  around  its  ends. 

In  her  account  of  T.  raiae  in  Pontobdella  Miss  Robertson  (I.e.) 
has  gone  at  length  into  the  question  of  nuclear  division.  The 
kinetonucleus  appears  to  divide  by  a  simple  kind  of  mitosis  though 

FIG.  19. 

A-D,  stages  in  the  binary  longitudinal  tission  of  7'.  r</»  inn  m  ;  K,  multiple  fission  in  the  same 
parasite  ;  F  and  G,  binary  and  multiple  division  in  T.  cfiuiperdum.    (After  Lignieres.) 

the  details  are  extremely  obscure.  The  trophonuclear  division  also 
takes  place  by  a  simple  kind  of  mitosis,  but  shows  a  well-defined 
achromatic  figure  (comparable  to  a  series  of  axial  fibrils).  This 
probably  arises  from  the  trophonuclear  centrosome.  The  figures 
showing  the  later  phases  of  the  process  convey  quite  the  same  idea 
as  does  Fig.  12  of  T.  grayi.  In  fact,  this  case  also  appears  to 
conform  to  the  same  general  plan  as  those  above  described. 

The  division  of  the  cytoplasm  takes  place  last.  In  the  great 
majority  of  forms  this  is  equal  or  sub-equal,  and  the  two  resulting 
daughter-Trypanosomes  are  of  approximately  the  same  size  (Figs. 
17  ;  19,  c).  Although  the  cytoplasmic  fission  usually  begins  at  the 
flagellar  end,  it  may  start  at  the  opposite  extremity  (cf.  Fig.  19,  D). 
In  some  instances  (Fig.  19,  E  and  G)  the  longitudinal  fission  is 


multiple,  the  original  individual  giving  rise,  simultaneously,  to  three 
or  four  descendants. 

T.  lewisi  differs  from  most  Trypanosomes  in  that  the  cytoplasm 
generally  *  divides  in  a  very  unequal  manner  (Fig.  20).  Indeed, 
the  process  is  more  comparable  to  budding,  since  the  larger  or 
parent  individual  may  produce,  successively,  more  than  one 

FIG.  20. 

Unequal  division  in  T.  lewisi.    m,  parent-individual ;  <7,  daughter-individual ;  rf1,  daughter- 
individual  dividing,     x  2000.    (A-E  after  Lav.  and  Mesn.  ;  F  after  Wasielewsky  and  Senn.) 

daughter-individual ;  moreover,  the  progeny  may  themselves  sub- 
divide before  separating,  the  whole  family  remaining  connected 
together  by  the  non-flagellate  end  (Fig.  20,  E  and  F).  In  this  type 
of  division,  it  may  be  noted,  the  kinetonucleus  comes  to  lie  alongside 
the  trophonucleus,  or  even  passes  to  the  other  side  of  it  (i.e.  nearer 
the  flagellar  end).  This  method  of  division  forms,  as  it  were,  a 

1  Swingle  (81)  lias  recently  found  that  T.  lewisi  may  also  divide  by  equal  binary 
fission  ;  and  in  such  cases  the  two  flagella  may  lie  on  opposite  sides  of  the  body. 




transition  between  binary  fission  and  the  other  characteristic  method 
of  T.  lewisi,  namely,  segmentation  or  rosette-formation  (Fig.  21). 
The  chief  difference  is  that,  in  the  latter,  no  parent-individual  is 
recognisable,  the  segmentation  being  equal  and  giving  rise  to  a 
rosette  of  equal  daughter-Trypanosomes. 

The  small  parasites  resulting  from  either  of  these  modes  of 
division  (Fig.  21,  E)  differ  from  typical  adults  by  their  stumpy,  pyri- 
form  shape,  the  position  of  the  kinetonueleus  near  the  fiagellar  end 
of  the  body,  and  the  absence,  during  the  first  part  of  their  youth, 
of  an  undulating  membrane.  At  this  period  they  have  a  somewhat 
Herpetomonas-like  aspect.  These  young  individuals  can  them- 

A-D,  segmentation  (rosette-formation)  in  T.  lewisi ;  in  C  nuclear  division  lias  finished  and 
the  daughter-nuclei  (of  both  kinds)  have  taken  up  a  superficial  position,  while  the  cytoplasm 
lias  become  lobulated  at  the  periphery,  prior  to  the  formation  of  the  daughter-Trypanosomes. 
E,  daughter-individual ;  F,  one  dividing,  x  1750.  (After  L.  and  M.) 

selves  multiply  by  equal  binary  fission,  giving  rise  to  little 
fusiform  parasites ;  and,  with  growth,  these  gradually  assume  the 
adult  appearance. 


It  may  be  safely  said  that  this  remains,  even  to-day,  one  of  the 
most  difficult  and  most  debated  questions  among  the  whole  of  the 
Protozoa,  in  spite  of  the  amount  of  work,  of  one  kind  or  another, 
which  has  been  contributed  to  the  subject  during  the  last  few 
years.  When  the  present  writer  compiled  his  Review  of  the 
Haemoflagellates  (3)  some  years  ago,  Schaudinn's  remarkable 
observations  had  been,  to  all  appearance,  amply  corroborated  in 
various  directions  by  the  testimony  of  the  Sergents  (77),  Billet 
(4,  5),  Brumpt  (9),  Leger  (50),  and  Rogers  (94) ;  in  short,  the 


whole  trend  of  research  pointed  at  the  time  to  a  very  complex 
life-cycle  of  the  Haemoflagellates  and  to  a  close  connection  with 
the  Haemosporidia.  Since  then,  however,  owing  in  a  great 
measure  to  the  work  of  Novy  and  M'Neal  on  the  Trypanosomes  of 
birds  (62)  and  of  mosquitoes  (63),  the  results  obtained  by 
Schaudinn  have  become,  to  a  large  extent,  discredited ;  these 
authors  maintaining  that  they  are  capable  of  a  quite  different 
interpretation.  Moreover,  influenced  by  their  work  on  Insectan 
Flagellates,  Novy  and  his  colleagues  have  gone  to  the  other 
extreme  and  expressed  their  belief  not  merely  that  Haemoflagellates 
and  Haemosporidia  are  entirely  distinct,  but  also  that  the  Trypano- 
somes of  Vertebrates  do  not  undergo  any  true  development  or  part 
of  their  life-cycle  in  the  Insectan  host.  This  latter  view,  at  all 
events,  is,  AVC  think,  shown  to  be  incorrect  by  the  most  recent 
research,  which,  as  above  mentioned,  seems  all  in  favour  of  an 
alternate,  Invertebrate  host,  one  of  the  most  important  indications 
being  with  regard  to  the  specificity  of  the  latter — a  point  of  the 
utmost  consequence  in  its  bearing  upon  investigations  of  this  kind. 
Leaving  aside  for  the  moment  a  consideration  of  Schaudinn's 
celebrated  memoir,  it  Avill  be  best  to  give  first  a  brief  account  of 
the  results  obtained  in  this  connection  by  different  prominent 
researchers,  to  other  aspects  of  whose  work  reference  has  been 
previously  made. 

Dealing  first  with  Trypanosomes  of  cold-blooded  Vertebrates, 
the  earliest  important  observations  are  those  of  Le"ger  (50),  relating 
to  Trypanoplasma  varium  and  Tri/panosoma  barbatulae  of  the  loach. 
Leger  distinguishes  ordinary  ("indifferent")  and  larger,  more 
granular  (probably  female)  forms  of  the  Trypanoplasma  in  the 
blood  of  the  fish.  When  a  leech  (Hemiclepsis  sp.)  was  allowed  to 
suck  blood  containing  only  these  parasites,  which  thereupon  passed 
into  its  stomach,  the  indifferent  forms  degenerated  and  perished, 
while  the  female  ones  became  massive  and  showed  nuclear  changes, 
preparatory,  Leger  thinks,  to  a  sexual  process.  At  any  rate,  after 
some  days,  the  intestine  of  the  leech  contained  numerous  little 
narrow  Trypanoplasms,  of  which  some,  very  filiform,  perhaps 
represented  male  forms,  while  others  possessed  a  kind  of  beak  or 
rostrum  in  place  of  the  anterior  flagellum,  which  made  them 
resemble  Trypanosomes.  The  development  of  Trypanosoma  bar- 
batulae in  another  leech  (Piscicola)  showed  a  certain  amount  of 
agreement  with  that  described  by  Schaudinn  in  the  case  of  his 
Avian  Trypanosome  in  the  gnat  (Culex).  Eighteen  hours  after 
the  leech  had  fed  on  blood  containing  exclusively  T.  barbatulae, 
pyriform  bodies  lacking  a  flagellum  ("  ookinetes ")  were  found  in 
the  intestinal  contents.  Some  of  these  had  a  single  large  nucleus 
ii.e,  a  compound  nucleus) ;  others  had  two  nuclei,  one  smaller  than 


the  other.  Four  days  later  the  intestine  contained  numerous 
Trypanosmes  which  could  be  readily  distinguished  as  belonging  to 
one  of  Schaudinn's  three  types — namely,  indifferent,  male,  or  female. 
The  male  forms  are  very  elongated  and  slender,  provided  with  a 
minute  rostrum  at  the  aflagellar  end,  and  with  a  well -developed 
flagellum  at  the  opposite  extremity,  which  renders  them  extremely 
active ;  they  also  creep  or  crawl  with  the  rostrum  in  front.  Their 
cytoplasm  is  very  clear  and  usually  lacks  granulations.  Female 
forms,  on  the  contrary,  are  large  and  broad,  with  deeply  staining, 
usually  granular  cytoplasm ;  the  flagellum  is  only  feebly  developed 
and  the  movement  is  sluggish.  The  indifferent  individuals  occupy 
in  most  respects  an  intermediate  position  between  the  other  two 
types.  A  point  of  importance  is  that  the  kinetonucleus  frequently 
lies  in  about  the  middle  of  the  body,  and  may  be  close  to  the 
trophonucleus.  There  can  be  no  doubt,  it  may  be  here  remarked, 
that  these  different  sets  of  forms  are  of  regular  occurrence  in,  at 
any  rate,  certain  Trypanosomes.  Since  Schaudinn  first  described 
them  several  observers  have  recognised  them,  in  some  instances  in 
the  Vertebrate  host,  but  always  more  sharply  differentiated  in  the 
Invertebrate.  In  general,  the  three  types  show  the  same  charac- 
teristics as  noticed  in  the  case  of  T.  barlatulae.  The  indifferent 
forms,  Leger  states,  underwent  active  multiplication,  by  equal 
fission ;  those  females  which  divided  did  so  very  unequally,  by 
a  process  somewhat  like  budding.  The  manner  and  form  in  which 
the  parasites  passed  back  into  the  fish  were  not  ascertained. 

'In  his  valuable  contributions  on  the  behaviour  of  Piscine 
Trypanosomes  in  leeches,  Brumpt  (11)  has  noted  developmental 
phases  of  T.  granulosum  of  the  eel  in  Hemidepsis.  Some  hours 
after  arrival  in  the  stomach  of  the  leech,  all  the  parasites  become 
pyriform,  and  by  the  position  of  the  kinetonucleus  close  to  the 
trophonucleus  recall  Lager's  Crithidia-typQ  (see  below).  By  active 
multiplication,  an  enormous  number  of  little  forms  are  produced, 
which  by  the  end  of  forty-eight  hours  have  nearly  all  passed  into 
the  intestine.  Here  they  rapidly  become  elongated,  assuming  a 
Herpetomonad-form,  which  may  be  retained  for  several  months. 
Some,  however,  by  the  end  of  seventy-two  hours,  have  given  rise  to 
true  Trypanosoma-forms,  with  typical  undulating  membrane,  which 
pass  forwards  towards  the  stomach,  and  may  be  found  accumulated 
in  the  foremost  stomach-coeca  and  in  the  proboscis-sheath  by  the 
fifth  day.  These  are  the  forms  which  are  inoculated  into  the  eel, 
becoming  by  simple  elongation  ordinary  T.  granulosum  again. 

Miss  Robertson  has  published  (72)  some  interesting  observations 
on  a  Trypanosome  met  with  in  Pontobdella  muricata,  which  she 
regards  as  T.  raiae.  This  view  is  rendered  extremely  probable  from 
the  fact  that  Brumpt  (10)  has  found  that  T.  raiae  does  develop  in 
Pontobdella.  According  to  both  authors  the  earliest  phases  occurring 


are  rounded  forms  with  both  nuclei  but  no  locomotor  apparatus — 
comparable  to  ookinetes,  in  short  (cf.  T.  barbatulae  above).  These 
individuals,  says  Miss  Eobertson,  which  divide  in  this  condition 
fairly  actively,  gradually  disappear  from  the  crop  and  are  found 
only  in  the  intestine.  Here  they  develop  a  locomotor  apparatus, 
but  persist  for  some  time  in  a  Crithidia-]\ke  form  ;  they  are  of 
varying  size  and  may  be  very  small.  Later  on,  these  individuals 
take  on  a  more  or  less  typical  Trypanosome-like,  or,  as  we  have 
previously  termed  it,  trypaniform  character,  with  the  kinetonucleus 
in  the  aflagellar  half  of  the  body,  though  its  actual  position  varies 
greatly.  These  trypaniform  individuals  are  of  two  main  types, 
which  appear,  however,  to  be  connected  by  intermediate  grades. 
One  kind  is  relatively  very  broad,  with  a  relatively  small  kineto- 
nucleus, but  usually  with  a  fairly  long  flagellum.  The  other  type 
is  a  long  slender  Trypanosome,  with  a  large  kinetonucleus,  but  the 
free  flagellum  is  not,  as  a  rule,  very  long.  The  constitution  of  the 
trophonucleus  presents  an  unusual  condition ;  it  is  very  much 
drawn  out,  and  the  chromatin  is  arranged  in  a  number  of  transverse 
rods  or  bars  (perhaps  comparable  to  chromosomes)  arranged  more 
or  less  parallel,  like  a  ladder  (cf.  author's  note  on  T.  brucii  above, 
p.  216).  About  the  middle  of  digestion,  these  Trypanosomes  occur 
chiefly  in  the  intestine,  but  also  in  the  crop,  often  in  large  numbers. 
At  a  later  period,  a  still  more  slender,  practically  thread-like  form  is 
developed,  which  is  met  with  chiefly  in  the  proboscis,  though  also, 
apparently,  in  the  intestine.  This  type,  which  differs  rather  from 
the  last,  appears  to  die  off  if  it  remains  in  the  leech,  and  taking 
this  in  conjunction  with  the  occurrence  of  these  individuals  in  the 
proboscis,  the  inference  is  that  this  is  the  form  in  Avhich  the 
parasites  are  inoculated  into  the  fish.  At  the  close  of  digestion, 
a  number  of  very  small  forms  are  always  to  be  seen,  either  in  a 
rounded  (probably  resting)  condition  or  in  a  very  early  Crithidial 
phase.  These  seem  to  be  persistent  forms,  through  which  the 
leech  retains  the  infection. 

Miss  Robertson  discusses  the  likelihood  of  the  two  contrasting 
trypaniform  types  above  described  representing  male  and  female 
individuals,  but  for  several  reasons  hesitates  to  accept  this  view. 
However  this  may  be,  it  is  more  probable  that  conjugation  itself 
takes  place  soon  after  the  transfer  of  the  parasites  from  one  host  to 
the  other,  i.e.  after  the  arrival  in  the  Invertebrate ;  and  that  the 
ookinete  form  is  the  immediate  result  of  the  process.  This  is 
suggested  by  Lager's  work  on  T.  barbatulae,  as  well  as  by  Keysse- 
litz's  account  of  the  life-cycle  of  Trypanoplasma  borreli  (27).  It 
is  also  regarded  by  Prowazek  (68)  as  being  the  case  in  T.  leivisi,  in 
the  louse. 

According  to  Keysselitz,  male  and  female  gametes  can  be 
readily  recognised  in  the  blood  of  the  fish  (carp),  the  conjugation 


taking  place  in  the  leech,  after  various  regulatory  or  matura- 
tion processes  have  been  undergone.  The  copulae  give  rise  to 
the  three  general  types,  distinguished  principally  by  nuclear 

In  the  case  of  T.  lemsi,  Prowazek  states  that  soon  after  reaching 
the  mid-gut  of  the  louse,  the  parasites  undergo  reduction  of  the 
nuclear  apparatus,  by  which  the  number  of  chromosomes  is  said 
to  be  reduced  from  sixteen  to  four.  The  gametocytes  (parent- 
individuals  of  the  gametes)  are  not  strikingly  differentiated  from 
one  another,  but  in  the  formation  of  the  microgamete  from  the 
male  form,  the  body  becomes  diminished  in  size,  its  nucleus 
(trophonucleus)  very  elongated  and  at  first  spirally  twisted,  then 
band-like,  while  also  the  cytoplasm  stains  differently  from  that  of 
the  female  element  (megagamete). 

Coming  now  to  what  is  known  of  the  development  of  Mam- 
malian Trypanosomes  in  Tsetse -flies  (Glossinae),  we  have  first  to 
mention  the  knowledge  obtained  by  Minchin,  Gray,  and  Tulloch  (59) 
with  regard  to  T.  gambiense  in  G.  palpalis.  This,  unfortunately,  ia 
largely  of  a  negative  character,  owing  in  all  probability  (as  we  have 
seen  earlier)  to  this  species  of  fly  not  being  the  correct  alternate 
host,  but  one  in  which  the  attempts  of  the  parasite  to  continue  its 
life-history  are,  for  some  reason,  unsuccessful.  Nevertheless,  the 
important  observation  that  the  types  already  recognised  as  male 
and  female  in  the  blood  of  the  Vertebrate  at  first  greatly  pre- 
dominate, with,  moreover,  a  much  more  marked  differentiation 
of  sexual  characters  and  without  any  forms  intermediate  in 
type,  is  also  strongly  in  favour  of  the  idea  that  conjugation 
occurs,  in  general,  soon  after  the  arrival  of  the  Trypanosomes  in 
the  insect. 

No  mention  is  made  by  Stuhlmann  (80),  in  his  highly  interest- 
ing account  of  T.  brudi  in  G.  fusca,  of  the  occurrence  of  any  similar 
phases,  or  of  anything  in  the  nature  of  ookinetes,  at  the  beginning 
of  the  infection.  The  first  individuals  found  by  this  investigator 
were  of  the  indifferent  type,  occurring  in  large  numbers  in  the 
hinder  part  of  the  gut,  two  to  four  days  after  infection  of  the  fly. 
It  seems  probable,  however,  that  Stuhlmann  missed  some  early 
essential  phases  of  the  development,  since,  as  said  above,  Le"ger 
found  ookinetes  of  T.  barbatulae  eighteen  hours  after  feeding,  while 
Minchin  and  his  collaborators  say  that  the  sexual  forms  were  best 
developed  after  about  twenty-four  hours,  while  by  the  end  of  forty- 
eight  hours  a  type  of  more  indifferent  character  was  making  its 
appearance.  According  to  Stuhlmann,  the  indifferent  parasites 
apparently  spread  forwards  through  the  mid-gut,  but  usually  pass 
right  forward  only  when  the  flies  are  fed  again  (from  an  uninfected 
animal).  By  this  means  the  presence  of  the  Trypanosomes  in  the 
proventriculus  was  obtained,  and  in  the  "long"  form,  quite  similar 


to  the  type  occurring  in  the  proventriculus  and  oesophagus  of  freshly 
caught  "  wild  "  flies. 

This  type  manifestly  corresponds  to  Miss  Robertson's  very 
slender  forms  in  the  front  part  of  the  gut  and  proboscis  of  the 
leech  ;  the  agreement  extends  to  the  ladder-like  arrangement  of  the 
chromatin  (chromosomes  ?)  of  the  trophonucleus.  Whereas,  how- 
ever, in  T.  raiae,  it  is  these  forms,  or  their  derivatives,  which  appear 
destined  to  return  to  the  fish,  Stuhlmann  found,  in  the  proboscis 
of  freshly  caught  Tsetses,  little  Crithidial  forms  ("small"  forms), 
with  the  kinetonucleus  alongside,  or  on  the  flagellar  side  of  the 
trophonucleus.1  Stuhlmann  regards  these  individuals,  which  he  was 
unable  to  obtain  in  artificially  infected  flies,  as  representing  the 
phase  in  which  T.  brutii  is  transmitted  to  the  Vertebrate ;  though 
lie  states  that  the  long  forms  seem  to  degenerate  in  the  pro- 
ventriculus after  a  time  (as  well  as  the  small  ones).  In  no  case, 
unfortunately,  was  he  able  to  actually  infect  a  Vertebrate  by  means 
of  either  kind,  which  suggests  that  there  is  some  other,  as  yet 
unknown,  factor  or  condition  concerned  in  this  perplexing  question. 

Stuhlmann  describes  and  figures  certain  phases  found  in  one  case 
in  the  proventriculus  of  an  artificially  infected  fly,  which  he  thinks 
are  perhaps  indicative  of  conjugation.  In  all  the  stages  figured, 
the  cytoplasmic  body  of  the  parasite  is  single ;  the  nuclear  and 
locomotor  organellae,  on  the  other  hand,  show  different  conditions 
from  single  to  double.  Of  course,  here  as  in  so  many  other  cases, 
it  is  entirely  a  matter  of  the  sequence  in  which  the  figures  should 
be  taken.  Stuhlmann's  chief  reason  for  his  interpretation  is  that, 
in  what  he  regards  as  the  earlier  stages  of  union,  the  flagella  lie  on 
opposite  sides  of  the  body ;  whereas,  in  the  usual  mode  of  division, 
the  two  flagella  lie  on  the  same  side  of  the  body.  Still,  Stuhlmann 
himself  agrees  that  the  condition  may  be  only  one  of  an  unusual 
mode  of  division ;  and  this  seems  the  more  likely  explanation,  for 
such  a  mode  of  division  has  been  observed  in  T.  lewisi.2 

That  the  course  of  a  Trypanosome  life-cycle  may  take,  however,  a 
quite  different  direction  from  that  outlined  in  the  above  instances  is 
proved  unmistakably  by  Minchin's  valuable  investigations  on  Trypano- 
soma  graiji  (57  and  58),  which  led  him  to  the  unexpected  discovery 
of  the  encystment  of  this  form  in  the  proctodaeum  of  G.  palpalis. 

Minchin  recognises  three  well-marked  types  of  this  Trypanosome 
in  the  fly.  (a)  The  ordinary  type,  having  a  multiplicative  function, 
and  probably  giving  rise  to  the  swarm  of  parasites  often  found.  It 
is  usually  of  large  size,  and  shows  great  variability,  especially  in 
the  position  of  the  kinetonucleus.  While  generally  a  little  in  front 
(i.e.  on  the  flagellar  side)  of  the  trophonucleus,  it  may  be  alongside, 

1  For  an  account  of  the  proboscis  -  forms  recently  described  by  Roubaud,   see 
Postscript,  p.  261.  2  Cf.  footnote,  p.  225. 



or  even  behind  it  (i.e.  nearly  terminal  at  the  afiagellar  end),  though 
it  is  not  often  in  the  last  position.  Minchin  thinks  this  last  form 
most  nearly  represents  that  in  which  T.  grayi  occurs  in  its  Vertebrate 
(probably  Avian)  host.  The  second  type  (b}  is  constituted  by 
slender,  often  greatly  elongated  individuals,  with  well-developed 
undulating  membrane  and  flagellum.  Minchin  was  at  first  inclined 
to  regard  these  as  male  forms ;  but  from  their  occurrence  in  one 
case  in  remarkable  numbers  in  the  proctodaeum,  to  the  exclusion 
almost  entirely  of  any  other  kind,  he  has  since  thought  this  view 
to  be  unlikely.  The  primary  habitat  of  the  slender  type  is  the 
proctodaeum,  from  which  region  it  may  extend  forward  through 
the  intestine  and  stomach  of  the  fly.  (c)  Small,  very  narrow  forms, 
of  a  typical  Herpetomonas-Yike  structure,  practically  lacking  any 

undulating  membrane  (Fig. 
22,  a),  which  stain  more 
faintly  and  appear  much 
more  delicate  than  parasites 
of  type  (b);  the  kinetonucleus 
is  often  relatively  large. 
These  individuals  were  found 
in  the  proctodaeum,  and, 
rarely,  in  the  hinder  intes- 
tine ;  they  are  apparently 
derived  from  young  forms  of 
the  indifferent  type,  pro- 
duced by  rapid  multiplication 
in  the  hinder  part  of  the 

It  is  this  Herpetomonad 
type  which  undergoes  en- 
cystment.  In  cyst-formation 
the  flagellum  becomes 
shortened  and  at  the  same 

time  apparently  thickened.  The  cyst  begins  to  appear  as  a  layer 
of  substance,  probably  of  a  slimy  or  mucoid  nature  (cf.  Prowazek's 
"  Schleimcysten "  in  the  case  of  Herpetomonas  muscae-domesticae 
[69]),  which  forms  a  cap  at  the  aflagellar  end  (Fig.  22,  b).  These 
two  processes  continue  until,  on  the  one  hand,  the  flagellum  is 
completely  retracted,  and,  on  the  other  hand,  the  body  is  enveloped 
in  a  pear-shaped  cyst  (c),  which  is  at  first  incomplete  at  the  pointed 
end.  The  flagellum  appears  next  to  become  retracted  into  a  pink- 
staining  vacuole  (cf.  the  opposite  process  in  the  formation  of  the 
flagellar  phase  of  Leishmania  (Piroplasma)  donovani) ;  finally,  the 
flagellar  vacuole  fades  away,  the  cyst  meanwhile  closing  up. 
Eventually  there  results  an  oval  or  circular  cyst,  containing  hyaline 
cytoplasm  and  the  two  chief  nuclear  masses  (d).  In  this  guise, 

FIG.  22. 

Encystrnerit  of  the  narrow,  Herpetomonad  form 
of  Trypanosoma  grayi.    (After  Minchin.) 


presumably,  T.  grayi  passes  into  the  outer  world,  to  be  swallowed 
subsequently  by  its  alternate  host.1 

Comparing  T.  grayi  with  T.  Irucii,  an  essential  point  of  contrast 
is  at  once  noticed.  In  the  first-named,  the  small,  Herpetomonad 
forms,  which  have  the  function  of  propagating  the  infection  to  a 
fresh  host,  occur  mainly  in  the  proctodaeum  and  leave  the  fly  per 
<ui urn.  In  the  latter,  on  the  contrary,  the  small,  Crithidial  forms, 
which  are  compared  by  Minchin  with  those  of  T.  grayi  just  men- 
tioned, were  found  almost  exclusively  in  the  proboscis ;  moreover, 
no  Trypanosomes  of  any  kind  Avere  seen  in  the  hindermost  part  of 
the  gut  (proctodaeum).  Hence  the  propagation  of  T.  Irucii  would 
appear  to  be  just  as  certainly  by  the  inoculative  method  as  that  of 
T.  f/rayi  is  by  the  contaminative  one.  Further,  just  as  there  is  at 
present  no  evidence  of  contaminative  infection  in  T.  brucii,  so  there 
is  none  of  inoculative  infection  in  T.  grayi ;  for  although  Minchin 
says  that  the  slender  type,  which  he  also  thinks  is  a  propagative 
form,  was  met  with  farther  forward  than  the  Herpetomonad  type, 
it  was  not  met  with  farther  forward  than  the  stomach.  And  this 
is  as  far  as  our  knowledge  goes  up  to  the  present. 

Schaudinn's  Work  on  Haematozoa  of  the  Little  Owl. 

There  remains  for  consideration  the  remarkable  research  of  the 
late  Fritz  Schaudinn  on  certain  parasites  of  Athene  nodua  and  Culex 
pipiens,  namely,  I'rypanomorpha  (Trypanosoma)  noctuae  and  "  Try- 
panosoma  "  (Lemocytozoon,  Spirochaeta)  ziemanni.  Exigencies  of  space 
preclude  a  detailed  account  of  this  work,  only  the  main  outlines 
of  which  can  be  given  here,  but  a  full  description  will  be  found  in 
the  writer's  article  on  the  Haemoflagellates  (3). 

Taking  first  Trypanomorplw,  noctuae,  the  life -cycle  may  be  con- 
veniently commenced  with  the  motile  copula  or  ookinete  resulting 
from  conjugation  in  the  stomach  of  the  gnat.  While  the  nuclear 
fusion  of  the  two  sets  of  elements  (kinetic  and  trophic)  derived 
from  the  original  gametes  is  being  completed,  leading  to  a  single, 
large,  compound  nucleus,  the  ookinete  is  getting  rid  of  unnecessary 
material,  such  as  the  pigment-grains  and  reduction-nuclei  left  over 
in  the  cytoplasm  (Fig.  10,  A,  B).  Even  in  the  ookinete  stage, 
Schaudinn  recognises  the  three  types  of  individual,  indifferent, 
male,  and  female,  distinguishable  by  differences  in  the  size  of 
the  nuclei  relative  to  the  cytoplasm,  and  by  the  varying  appear- 
ance of  the  latter. 

The  development  of  an  indifferent  Trypanosome  has  been  de- 
scribed above  (p.  213).  When  formed,  a  period  of  active  movement 
and  multiplication  sets  in,  succeeded  later  by  a  resting  condition.  The 

1  The  reasons  for  considering  that  this  parasite  is  not  merely  a  "  fly-parasite  " 
have  been  given  on  p.  201. 


parasites  now  become  gregariniform,  and  strongly  recall  the  similar 
phase  described  by  Le"ger  (48,  51)  in  certain  Herpetomonads.  The 
Trypanosome  bores  into  an  epithelial  cell  of  the  stomach  by  means 
of  its  flagellum,  which  is  reduced  to  a  short,  rod- like  organella. 
Binary  fission  may  go  on,  often  leading  to  the  formation  of  a  dense 
layer  of  attached  parasites.  On  the  parasites  again  becoming  try- 
paniform,  the  flagellar  apparatus  is  reconstituted  by  the  kineto- 
nucleus.  This  alternation  of  resting  and  active  periods  is  limited. 
Eventually  the  indifferent  Trypanosomes  may  pass  into  the  blood 




FIG.  23. 

Development  of  microgametocyte  and  male  Trypanosomes  from  an  ookinete  of  male  character, 
(After  Schaudinn.)  m.n,  male  nuclei;  f.n,  degenerating  female  nucleus;  m.t,  male  tropho- 
nucleus  ;  m.k,  male  kinetomicleus  ;  M.T,  male  Trypanosome  ;  r.b,  residual  body. 

of  the  owl ;  or  they  may  apparently  become  sexual  forms,  male 
or  female ;  or  else,  during  a  period  of  hunger,  they  die  off. 

In  the  development  of  an  ookinete  of  male  character,  or  micro- 
gametocyte, there  is  an  early  separation  of  the  nuclear  constituents 
into  two  halves,  male  and  female.  The  female  portion  consists  of 
a  large,  loose  nucleus  (Fig.  23,  C  and  D,  f.n),  which  gradually 
degenerates  and  disappears.  The  male  portion,  on  the  other  hand, 
gives  rise  to  eight  little  double-nuclei  (c  and  D,  m.n),  each  consisting 
of  trophic  and  kinetic  portions.  The  microgametocyte  now  becomes 
rounded,  the  eight  double-nuclei  take  up  a  peripheral  position  (E),  and 
the  cytoplasm  opposite  each  grows  out  as  a  little  prominence.  As- 


these  elongate,  each  accompanied  by  a  double-nucleus,  they  take  on 
a  trypaniform  appearance,  which  is  completed  by  the  development 
of  a  flagellum.  Finally,  the  eight  little  male  Trypanosomes  (F,  .v.r), 
which  are  homologous  with  microgametes,  break  away  from  the 
central  residuum.  These  forms  are  apparently  incapable  of  further 
development  in  any  way  and  soon  die  off.  Schaudinn  accounts  for 
this  by  the  condition  of  the  trophonucleus,  which,  he  says,  has 
undergone  reduction. 

The  early  stages  in  the  formation  of  a  female  Trypanosome  are 
similar  to  those  in  the  case  of  a  microgametocyte.  Here,  however, 
it  is  the  eight  small  double- 
nuclei,  representing  the 
male  constituents,  which 
degenerate,  leaving  the 
large  female  nucleus  to 
become  differentiated  and 
give  rise  to  the  locomotor 
apparatus  in  the  same  way 
as  in  an  indifferent  form 
(Fig.  24,  c).  In  the 
females  the  flagellum,  etc., 
is  poorly  developed,  and 
the  movements  of  the  para- 
sites are  slow  and  feeble. 
These  Trypanosomes  seem 
unable  to  divide.  They 
grow  to  a  large  size,  and 
store  up  a  considerable 
amount  of  reserve -nutri- 
ment in  the  cytoplasm. 
These  forms  are  the  most 
resistant  to  external  in- 
fluences, and  can  survive 

long  hunger-periods,  in  a  gregariniform,  resting  condition.1  With 
the  advent  of  fresh  blood  into  the  stomach  of  the  gnat,  the  female 
forms  undergo  a  process  of  parthenogenesis,  consisting  of  nuclear 
reduction  and  a  kind  of  self-fertilisation.  Thus  rejuvenated,  they 
are  able  to  give  rise  to  a  fresh  succession  of  Trypanosomes  of  all 
three  types. 

The  Behaviour  and  Development  of  the  Trypanosomes  in  the  Blood  of 
tJie  Owl. — All  the  Trypanosomes  met  with  in  the  bird  can  be  recog- 
nised as  belonging  to  one  of  the  three  categories  observed  in  the 
gnat.  On  entering  the  blood,  the  small  indifferent  forms  at  once 

1  According  to  Schaudinn,  these  gregariniform  females  can  bring  about  hereditary 
infection,  remaining  dormant  in  the  ovaries  until  the  eggs  are  laid  and  the  larvae 

Development  of  a  female  Trypanosome  from  an 
ookinete  of  female  character.  (After  Schaudinn.) 
m.n,  degenerating  male  nuclei ;  a.sp,  tirst  axial  spindle 
of  female  nucleus;  f.t,  female  trophonucleus;  /./,-, 
female  kinetonucleus. 



attach  themselves  to  the  red  blood -corpuscles  (Fig.  25,  A  and  B), 
and  begin  a  period  of  rest  and  growth.  The  locomotor  apparatus 
disappears  and  the  two  nuclei  come  close  together.  The  form  of 
the  parasite  is  now  quite  that  of  a  young  Halteridium,  a  well-known 
malarial  parasite  of  birds,  and,  moreover,  in  twenty-four  hours  the 
first  pigment-grains  appear  in  the  cytoplasm  (c).  By  this  time  the 
parasite  has  greatly  increased  in  size.  It  becomes  vermiform  and 
active,  reconstitutes  its  flagellum,  etc.,  and  leaves  the  host-cell  (D), 
usually  in  the  night-time,  becoming  once  more  a  typical  Trypano- 
morpha  (E).  This  alternation  of  attachment  and  growtli  with  active 
movement  in  the  plasma  is  repeated  for  six  days,  until  the  full  size 
of  the  parasite  is  attained  (F  and  G).  The  adult  Trypanosome  then 
undergoes  successive  longitudinal  divisions,  until  the  resulting 
daughter -individuals  have  reached  a  minimum  size,  when  they 
repeat  the  whole  cycle.  It  is  worth  noting  that  Schaudirm  never 


FIG.  25. 

Stages  in  the  growth  of  an  indifferent  Trypanosome  in  the  blood  of  the  owl.    n,  nucleus 
of  red  blood-corpuscle  ;  p,  young  ectocorpuscular  parasite.    (After  Schaudinn.) 

observed  any  multiplication  of  the  parasites  in  the  gregariniform 
(Halteridium)  condition,  by  schizogony,  such  as  is  met  with  in  other 

Microgametocytes  (male  forms)  arise  from  very  young  indifferent 
Trypanosomes.  Each  gives  rise  to  eight  small,  slender  micro- 
gametes,  in  the  same  way  as  do  the  corresponding  forms  in  the 
gnat.  The  microgametes  are  very  specialised  organisms.  The 
trophonucleus  (in  a  reduced  condition)  forms  a  long  thread,  on 
which  four  chromosomes  are  strung  at  intervals.  There  is  no  free 
flagellum  at  the  anterior  end,  but  the  body  has  a  whip -like  tail 

The  full-grown  megagametocytes  are  large  female  Trypano- 
somes, which  are  no  longer  able  to  assume  the  trypaniform  con- 
dition, but  remain  enclosed  by  the  pallid  and  disorganised  host-cell 
which  they  were  last  able  to  penetrate.  In  other  words,  they  are 
identical  with  the  female  gametocytes  of  Halteridium.  Maturation 



and  fertilisation  do  not  take  place  until  the  sexual  forms  are  trans- 
ferred to  the  gnat.  The  process  in  its  main  outlines  has  been 
previously  described  by  MacCallum  in  another  species  of  Halteridium.1 
Schaudinn  adds  that,  as  soon  as  the  parasites  leave  the  warm- 
blooded host,  the  megagametocytes  become  rounded  off,  rupture  the 
delicate  envelope  still  surrounding  them,  and  then  undergo  a  series 
of  reduction-divisions,  after  which  they  are  ready  to  be  fertilised. 
The  zygote  develops  into  one  of  the  three  kinds  of  ookinete  with 
Avhich  this  description  began. 

Leucocytozoon  ("  Trypanosoma  ")  ziemanni. — Even  more  surprising 
are  the  data  put  forward  by  Schaudinn  in  the  case  of  the  other  para- 
site (or  set  of  parasites)  upon  which  he  worked.  Just  as  a  species 
of  Halteridium  is  regarded  as  ontogenetically  related  to  Trypanomorpha 
noctuae,  so  Leucocytozoon  ziemanni,  a  parasite  of  the  white  corpuscles 
and  erythroblasts,  is  said  to  be  intimately  connected  with  what  has 
been  hitherto  taken  for  a  species  of  the  genus  Spirochaeta,  a  well- 
known  bacterial  type.  Far  from  being,  however,  a  true  member  of 
the  Bacteria,  this  species  at  any  rate  was  regarded  by  Schaudinn 
as  possessing  all  the  fundamental 
characteristics  of  a  Trypanosome 
(see  Fig.  7,  H). 

The  plan  of  the  life-cycle  is 
fundamentally  similar  to  that 
just  summarised,  the  same  sets 
of  forms  being  described.  Two 
or  three  distinguishing  features 
may  be  noticed.  The  indifferent 
Trypanosomes  are  extremely 
spirochaetiform  (Fig.  26,  A-D)  ; 
after  longitudinal  fission,  the 
two  daughter-individuals  remain 
attached  end-to-end  (B  and  c), 
the  resemblance  to  a  Spirochaete 
being  thereby  accentuated.2  The 
resting-phases,  little  pear-shaped 
forms  with  two  nuclear  elements 

(E    and    F),   are    Very   PiwplaSma-    zieimnni;'E,   F,   resting  -  phases  of  "same;   O", 
_'•  .  *  ,,         ,        agglomerated   cluster   of   very  minute    forms. 

like    and    strongly    recall     the  (After  Schaudinn.) 
Leishman-Donovan  bodies.     On 

the  other  hand,  the  gametocytes  (in  the  blood  of  the  owl)  are 
very  large  and  broad,  and  distinctly  trypaniform,  even  possessing 

1  See  the  account  of  the  Sporozoa,  by  Minchin,  in  this  treatise  (Vol.  I.  Part  II. ). 

3  According  to  Novy,  M'Neal  and  Torrey  (64),  Ttipfer  has  recently  cultivated  a, 
true  Spirochaete  (i.e.  a  Bacterium)  from  the  owl,  which  possesses  also  minute  resting- 
forms.  Hence  Schaudhm's  spirochaetiform  "  Trypanosoma "  may  have  been  really 
this  same  Spirochaeta. 


FIG.  20. 

;  formation  and  fission  of  spirochaeti- 
couples "  in  "  Trypanosoma  "  (Spirochaeta) 


well-marked  myonemes.  Prior  to  gamete-formation,  both  gametocytes 
come  into  relation  with  the  leucocytes,  in  an  unusual  manner  (see 
under  "  Habitat,"  p.  205),  and  lose  all  trace  of  locomotor  organellae. 

Microgamete  -  formation,  maturation 
and  fertilisation  of  the  megagamete 
(Fig.  27),  in  the  gnat,  present  nothing 
unusual.  Instead  of  an  ookinete 
giving  rise  to  a  single  Trypanosome, 
as  in  Trypanomorpha,  it  grows  con- 
siderably, forming  a  large  coil,  and 
nuclear  multiplication  goes  On  actively 
at  the  same  time  (Fig.  28).  Ulti- 
mately, an  enormous  number  of  little 
spirochaetiform  parasites  are  pro- 
duced, which  populate  the  alimentary 

tVip   crnnl- 
l6  §nat> 

^f  *V>^  ,         r.v.l^'k'l^       ^,V 

of  this  remarkable  work 

FIG.  27. 

Fertilisation  of  a  megagamete  by  a 
microgamete.  The  trophic  and  kinetic 
female  pronuclei  are  seen  on  the  left. 

Near  the  middle  lie  the  two  reduction- 

nuclei.   The  remains  of  the  host  -ceil  js  based  mainly  upon  the  realisation 

together  with  the  cast-off  envelope  of  .  f  i 

(After    that,    in     SUcll    a     Complicated     Study, 
,,  /.  ••,-, 

there  was  a  grave  source  of  possible 
error,  and  there  is  nothing  to  show  that  this  was  eliminated. 
The  opinion  has  been  very  generally  expressed  that  Schaudinn 
did  not  sufficiently  guard  against  the  liability  of  confusing  and 
mixing  up  the  life  -histories  of  entirely  distinct  parasites.  In 

the  parasite  are  on  the  right. 


FIG.  28. 

Growth  and  metamorphosis  of  an  indifferent  ookinete  ;  in  C  nuclear  multiplication  is  well 
advanced.    (After  Schaudinn.) 

the  first  place,  it  is  said  that  in  the  species  of  owl  used  at  least 
four  separate  Haematozoa  occurred :  two  free  parasites,  namely, 
a  Trypanosome  and  a  Spirochaete  ("  Trypanosoma "  ziemanni)  • 
and  two  intracellular  ones,  a  Halteridium  and  a  Leucocytozoon.  It 
may  be  at  once  admitted  that  this  is  quite  possible.  At  any  rate, 
the  entire  subject  is  reopened  and  cannot  be  settled  definitely  until 


the  life-cycle  of  some  or  of  all  the  parasites  concerned  has  been 
reinvestigated.  (See  Note  below.) 

While  preserving  an  open  mind  upon  the  matter,  the  writer 
would  point  out  that,  if  no  indubitable  confirmation  of  Schaudinn's 
far-reaching  conclusions  can  be  said  to  have  been  furnished,  the 
merely  negative  evidence  adduced  by  Novy  and  his  colleagues  is 
by  no  means  sufficient  proof  of  their  erroneousness.  Because  the 
injection  of  cultures  of  certain  Trypanosomes  in  artificial  media,  into 
birds,  was  not  followed  by  the  appearance  of  Cytozoa  in  the  blood, 
these  workers  apparently  conclude  (I.e.)  that  there  is  no  connection 
whatever  between  these  two  groups  of  Haematozoa.  And  this  com- 
prehensive generalisation  is  put  forward,  although  in  nearly  all  cases 
they  failed  to  obtain  even  a  Trypanosome-infection  by  this  means, 
apart  altogether  from  the  question  whether  the  particular  form  with 
which  they  did  once  succeed  had  itself  an  intracellular  phase  ! 

We  will  admit  that  the  cultivation-method,  which  is  of  undoubted 
use  in  other  ways,  may  not  be  without  value  in  studying  the  life- 
history.  In  certain  cases,  for  example,  the  behaviour  of  the  parasites 
on  their  arrival  in  the  culture-medium  may  to  some  extent  indicate 
or  suggest  what  happens  when  they  pass  into  the  Invertebrate 
host,  because  of  the  general  similarity  of  the  physical  conditions, 
etc.,  to  which  they  are  at  first  subjected.  An  illustration  of  this 
is  afforded  by  the  development  of  the  Flagellate  phases  of  the 
Leishman-Donovan  bodies  in  cultures.  Nevertheless,  we  certainly 
think  that  the  value  (in  this  respect)  of  the  cultural  method  of  re- 
search is  limited,  and  that  great  caution  is  necessary  in  drawing  infer- 
ences as  to  a  parasite's  life-history  from  the  results  obtained  by  it. 
We  dissent  entirely  from  the  American  authors  when  they  maintain 
that  the  culture-medium  is,  for  all  practical  purposes,  the  equivalent 

Note. — The  present  \vriter  has  always  been  reluctant  to  think 
Schaudinn  made  such  a  series  of  mistakes.  It  has  always  seemed  to  him 
that  this  author's  celebrated  work  on  the  Coccidia  of  Lithobius  has  not 
been  taken  into  account  sufficiently  by  those  who  have  maintained  that 
he  was  hopelessly  wrong  in  the  case  of  the  parasites  of  the  Little  Owl. 

It  is  with  the  greatest  pleasure,  therefore,  that  on  the  point  of 
publication  of  this  article,  the  writer  is  able  to  add  that  after  a  most 
arduous  investigation  on  the  Haematozoa  of  the  common  chaffinch 
(Fringillu  coelebs),  he  has  at  length  obtained  the  first  definite  and 
iinmistakable  evidence,  of  which  he  is  aware,  in  favour  of  one  of 
Schaudinn's  conclusions.  Here,  there  is  only  room  to  .«ay  that,  as  a 
result  of  his  observations,  he  has  now  little  doubt  that  a  Halteridium 
parasitic  in  the  chaffinch  becomes  actually,  in  certain  phases,  a  little 
Trypanosome ;  in  other  words,  that  the  Halteridium  and  the  Try- 
panosome  which  occur  in  this  bird  are  ontogenetically  connected  (vide 
Q.J.  Micr.  Sci.  liii.  p.  339,  Feb.  1909).  Hence  the  writer  feels  reassured 
with  regard  to  the  truth  of  the  corresponding  part  of  Schaudinn'a  work. 


of  the  medium  in  the  Insectan  host ;  on  the  contrary,  we  consider 
that  the  former,  whatever  indications  it  may  furnish,  cannot  replace 
altogether  the  latter. 

It  seems  to  us  that  Novy  and  M'Neal  entirely  fail  to  appreciate 
the  intimate  and  specific  relations  of  Protozoan  parasites  to  their 
hosts,  and  the  remarkable  degree  to  which  their  biology  is  adapted 
to  the  same.  The  Sporozoa  in  their  entirety  illustrate  this,  so  do 
other  parasitic  Protozoa,  and  there  is  no  reason  to  suppose  the  Haemo- 
flagellates  are  different.  We  agree  fully  with  Brumpt  that  the 
chemical  and  physiological  medium  of  a  particular  Invertebrate  is 
essential  for  the  adequate  development  of  all  such  phases  of  the 
life-history  of  a  Trypanosome  as  may  be  undergone  outside  the 
Vertebrate  host.  And  the  various  researches  above  summarised, 
which  go  to  show  that  there  are  right  and  wrong  hosts  for  the 
parasites,  and  that  only  certain  "  ripe  "  phases,  the  outcome  of  the 
sojourn  in  the  right  host,  can  reinfect  the  Vertebrate  host  success- 
fully, afford  strong  support  to  this  view. 

Another  criticism  put  forward  by  Novy  and  M'Neal  and  others 
is  that  the  Flagellate  phases  found  in  the  mosquitoes  (Culex),  Avhich 
Schaudinn  regarded  as  belonging  to  Trypanomorpha  of  the  Little 
Owl,  were  in  all  likelihood  purely  Insectan  parasites,  of  a  Herpeto- 
monad  or  Crithidial  type,  which  had  nothing  to  do  with  the  blood 
forms.  Before  discussing  this  view  it  is  necessary  to  consider 
briefly  the  subject  of  these  Insectan  Flagellates,  one  which  is  also  of 
very  great  importance  because  of  its  bearing  upon  the  phylogeny 
and  derivation  of  the  Trypanosomes. 


(a)  The  Insectan  Flagellates. 

Several  of  the  earlier  workers  have  commented  upon  the  occur- 
rence of  Flagellates  in  mosquitoes.  Thus  in  1898  Ross  observed 
parasites  which  he  has  recently  (74)  compared  with  Leger's  genus 
Crithidia  in  Anopheles,  larva,  pupa,  and  imago.  A  similar  parasite 
was  found  by  Christophers  in  1901,  occurring  in  swarms  in 
Anopheles  and  Culex.  Durham,  again,  the  }rear  before,  had 
noticed  numerous  "  Trypanosomes  "  in  a  Stegomyia  which  had  fed 
upon  a  bat.  The  first  serious  contributions,  however,  to  our  know- 
ledge of  the  Flagellates  parasitic  in  Insects  are  Leger's  researches 
(47,  48,  51,  52),  1902-1904,  on  certain  Herpetomonadine  forms. 

Besides  the  genus  Herpetomonas,  Le"ger  has  distinguished 
another  type  of  form,  which  he  has  termed  Crithidia.  Both  types 
show,  in  general,  an  alternation  of  monadine  (flagellate)  phases 
with  gregariniform  (resting,  non- flagellate)  ones.  In  the  latter 
condition,  the  parasites  occur  as  small,  rounded,  pear-shaped,  or 



even  oblong  bodies,  attached,  often  in  great  numbers,  to  the 
epithelial  cells.  The  flagellum  is  either  absent  or  reduced  to  a 
short  rostrum,  serving  for  attachment  (Fig.  29,  D  and  G).  The 
t\vo  nuclei  (tropho-  and  kinetonueleus)  lie  close  together,  usually 
near  the  base  of  the  cell.  In  this  phase,  the  general  resemblance 
to  the  Leishman-Donovan  bodies  may  be  quite  marked.  The 
distinction  between  the  two  generic  types  is  based  upon  the  form 
and  size  of  the  monadine  phase.  In  Herpetomonas  the  body  is  very 
elongated .  and  slender,  often  acicular,  the  posterior  end  usually 

FIG.  29. 

A,  C,  Herpetomonas  (Crithidia)  minuta  ;  D,  attached  (gregariniform)  phases  of  same;  B,  H. 
gracilis,  Leger  ;  E.  F,  //.  subulata,  Leger  ;  G,  attached  phases  of  same.  (After  Leger.)  x  1800. 

tapering  away  finely  (Fig.  29,  B  and  E).  In  Crilhidia,  on  the  other 
hand,  it  is  much  shorter  and  wider,  of  a  pyriform  shape  ;  the  hinder 
end  is  never  drawn  out,  but  terminates  bluntly  in  a  rounded  or  an 
obtuse  manner.  The  parasite  Herpetomonas  (Crithidia)  minuta,  L6ger, 
appears  to  be  intermediate,  however,  between  these  two  types,  some 
individuals  approximating  to  a  Herpetomonad  form  (A),  others  to  a 
Crithidial  one  (Fig.  29,  c).  As  a  matter  of  fact,  the  classificatory 
distinctions  between  these  various  Insectan  Flagellates  cannot  be 
regarded  as  at  all  settled. 

In  many  forms  of  Herpetomonas  (e.g.  H.  muscae-domesticae,1  H. 
jaculum,  or  H.  gracilis  (B)),  the  kinetonucleus  is  situated  near  the 

1  //.  muscae-domesticae  is  included  here  as  a  typical  uiiiflagellate  Herpetomonad. 
Prowazek  (69)  described  this  form  as  possessing  a  pair  of  flagella,  parallel  to  and 
connected  with  one  another  ;  he  considered  this  parasite  to  be  a  bipolar  type  (on  the 
lines  of  Schaudhm's  "  Urhaemoflagellate")  in  which  the  body  has  been  bent  up  so 
that  the  two  ends  have  come  together  and  united,  the  flagella  alone  remaining 
distinct.  Leger  observed  no  signs  of  two  flagella  in  non-dividing  individuals,  either 
of  this  species  or  others  ;  and  the  same  is  true  of  the  describers  of  the  numerous 
other  Herpetomonads. 



anterior  end  ;  the  flagellum  is  not  attached  to  the  side  of  the  body  at 
all  but  straightway  becomes  free,  and  there  is  no  sign  of  an  undulat- 
ing membrane.  These  forms  are  mostly  parasitic  in  Invertebrates 
which  do  not  suck  blood.  In  H.  subulata,  however,  which  is  parasitic 
in  the  digestive-tube  of  Tabanus  and  Haematopota,  predatory  on  cattle 
and  horses,  the  kinetonucleus  lies  much  farther  from  the  anterior 
end,  and  may  be  almost  opposite  the  trophonucleus  (Fig.  29,  F). 
The  flagellum,  which  has  been,  as  it  were,  drawn  back  with  it,  is  in 
most  individuals  attached  for  the  proximal  part  of  its  length  to  the 
anterior  part  of  the  booty,  by  means  of  a  delicate  cytoplasmic 
border,  which  constitutes  a  rudimentary  undulating  membrane. 
Thus  there  is  an  approach  to  a  trypaniform  condition.  Again,  in 
the  case  of  Crithidia  fasciculata,  found  in  the  intestine  of  mosquitoes, 
Leger  has  described  a  very  distinct  undulating  membrane,  which 
gives  the  parasite,  especially  in  the  more  elongated  individuals,  a 
very  Trypanosome-like  appearance.  Novy  and  his  colleagues  have 
also  studied  C.  fasciculata,  as  found  in  Culex  •  but  while  admitting 
the  presence  of  a  membrane,  regard  it  as  imperfect  and  only 
poorly  developed.  These  authors  describe,  in  addition,  another 
Herpetomonadine  type,  H.  (Trypanosoma)  culicis,  the  long  forms  of 
which  show  clearly  an  undulating  membrane. 

We  are  now  in  a  position  to  discuss  the  relation  (if  any)  of 
these  Flagellates  to  the  Trypanosomes  of  Vertebrates.  When 
first  describing  Crithidia,  Leger  expressed  the  opinion  that  this 
parasite  was  very  likely  only  a  stage  in  the  development  of  a 
Haemoflagellate ;  further,  in  his  notes  on  H.  subulata  (52)  he 
added  the  remark  that  the  same  was  probably  true  of  many  of  these 
Herpetomonad  or  Crithidial  forms  found  in  biting  Insects,  though 
this  would  not  apply,  of  course,  to  those  species  occurring  in  non- 
biting  Insects  (such  as  Musca,  Sarcophaga,  etc.).  Moreover,  Schaudinn 
himself  (I.e.)  comments  on  the  great  similarity  between  (what  he 
took  to  be)  the  phases  of  Trypanomorpha  noctuae  in  Culex  and  those  of 
Le"ger's  Crithidia. 

Quite  the  opposite  view  is  held  by  Novy  and  M'Neal,  who, 
after  first  (62)  regarding  the  Flagellates  found  by  Schaudinn  in 
mosquitoes  as  being  simply  "cultural"  forms,  of  no  real  significance 
in  the  life-history,  in  their  later  paper  (63)  consider  it  much  more 
likely  that  the  Insectan  parasites  are  entirely  distinct  from  the 
Trypanosomes  in  the  blood.  (They  look  upon  the  parasites  found 
in  leeches,  however,  as  "cultural"  forms  of  Piscine  Trypanosomes.) 
A  similar  opinion  is  expressed  by  Ross,  who  points  out  that  he 
found  Crithidia  in  the  mosquitoes  (larvae  and  pupae)  before  they 
fed  on  blood,  and  thinks  the  parasites  were  in  the  first  place 
swallowed  by  the  larvae. 

In  a  very  interesting  note  Patton  has  recently  (65)  described 


stages  in  a  Herpetomonas  of  Culex  pipiens,  whose  life-cycle  would 
seem  in  some  respects  to  conform  to  the  scheme  suggested  by  Ross. 
In  its  monadine,  determinative  form,  the  parasite  appears  to  be  a 
typical  Herpetomonas,  with  no  indications  of  an  undulating  membrane. 
All  the  phases  observed,  Patton  states,  exhibit  great  similarity  with 
those  of  Piroplasma  donovani  (see  pp.  256  et  seq.).  Here  it  may  be 
pointed  out  that  in  the  larvae  the  parasites  resembled  the  Leishman- 
Donovan  bodies  as  they  occur  in  human  tissues ;  in  the  nymphs, 
stages  corresponding  to  the  developmental  forms  of  the  Leishman- 
Douovan  bodies  (in  cultures,  or  in  the  bed-bug),  i.e.  pear-shaped  forms 
with  flagella,  were  numerous  ;  while  in  adult  mosquitoes  (mid-  and 
hind-gut)  there  were  fully  developed  Herpetomonad  forms.  Patton 
thinks  these  are  passed  out  into  the  water,  and  in  some  guise  or  other 
ingested  by  the  larvae,  the  cycle  thus  beginning  again.  (He  has 
privately  informed  the  writer  that  the  parasites  may  encyst  in  the 
rectum,  and  be  thus  passed  out  to  the  exterior,  to  give  rise  to  the 
small  round  forms  in  the  larva.)  Patton  also  notes  the  occurrence 
of  a  Herpetomonad,  which  has  an  obvious  undulating  membrane, 
and  which  possesses  similar  rounded  aflagellar  forms,  in  a  water- 
bug.  The  author  concludes  by  regarding  these  two  parasites  as 
limited  to  their  Insectan  hosts. 

In  endeavouring  to  draw  some  general  conclusions  from  the 
above  opposing  ideas,  we  are,  it  seems  to  the  writer,  greatly  helped 
by  comparing  what  is  known  in  the  case  of  other  groups  of  Trypano- 
somes.  In  the  first  place,  as  regards  those  met  with  in  Tsetse-flies, 
some  of  which,  at  any  rate,  were  formerly  considered  to  be  solely 
fly-parasites,  there  appears  to  be  no  escape  from  the  conclusion  that, 
on  the  contrary,  all  the  forms  are  blood-parasites.  In  our  opinion 
the  utmost  weight  is  to  be  attached  to  this  conclusion.  In  addition, 
we  have  the  Trypanosomes  of  leeches,  which  are  generally  agreed  to 
belong  to  different  Piscine  forms.  On  these  grounds  alone,  then,  it 
appears  justifiable  to  suppose  that  Avian  -Trypanosomes  are  to  be 
found  in  mosquitoes,  and  not  at  all  improbable  that  some  at  least 
of  the  phases  so  clearly  described  by  Schaudinn  from  mosquitoes 
which  had  fed  on  infected  owls,  did  indeed  appertain  to  Trypano- 
morpha  noduae. 

Again,  to  consider  the  subject  from  the  Insectan  standpoint,  so 
far  as  the  writer  can  see,  Novy  and  his  colleagues  have  by  no 
means  proved  that  their  Flagellates  in  wild  mosquitoes  are  not,  in 
some  cases  at  any  rate,  phases  of  Trypanosomes  of  birds  (or  other 
Vertebrates).  For  instance,  the  Trypaiwsoma  (Herpetomonas)  culicis 
described  by  these  authors — with  various  forms  of  which  they 
compare  certain  phases  of  Trypanomorplia — is  quite  as  probably  a 
blood-parasite  as  a  purely  Insectan  form ;  indeed,  the  possibility  of 
this  being  so  is  admitted  by  its  describers.  Moreover,  they  remark 
on  the  resemblance  between  the  genera  Herpetomonas,  Crithidia,  and 


Trypanosoma,  especially  when  the  "cultural"  forms  of  the  last-named 
are  compared  with  those  of  the  other  two  (or  with  what  Novy  and 
M'Neal  regard  as  their  equivalents — the  Insectan  forms).  In  the 
case  of  the  Trypanosomes,  there  is  the  same  relative  position  of  the 
two  nuclei,  either  close  together,  or  the  kinetonucleus  even  on  the 
flagellar  side  of  the  trophonucleus  ;  while  certain  of  them  show  no 
sign  of  an  undulating  membrane,  but  have  a  typically  Herpetomonad 
facies.  Novy  and  M'Neal,  in  fact,  would  include  all  these  types  in 
the  genus  Trypanosoma. 

Further,  we  may  point  out  that  according  to  the  view  which 
these  authors  themselves  hold  regarding  the  origin  of  the  blood- 
Try  pan  osomes,  it  is  most  natural  to  suppose  that  they  are  to  be 
met  with,  quite  at  home,  in  an  Insectan  host.  The  American 
workers  say  that  parasitism  in  the  living  blood  is  to  be  looked  upon 
as  the  result  of  previous  adaptation  to  the  more  or  less  digested 
blood  (in  the  Invertebrate).  (As  will  be  seen  later,  we  agree  with 
this  view,  where  certain  Insects  are  the  Invertebrate  hosts.)  Now, 
in  this  course  of  evolution  of  certain  blood-Trypanosomes,  it  may 
be  reasonably  inferred  that  at  one  stage  the  parasites  still  remain 
connected  with  the  Invertebrate  after  having  gained  a  footing  in  the 
Vertebrate  (say  a  bird).  The  question  would  seem  to  be,  rather, 
which  if  any  blood-forms  so  descended  have  lost  the  ability  to  live 
(and  develop)  in  their  Invertebrate  host — a  course  which  would 
probably  greatly  restrict  their  opportunities  for  dispersal.  (In  this 
connection  the  case  of  the  Leishman-Donovan  bodies  is  most 
instructive ;  cf.  pp.  258,  259.) 

Hence,  summing  up,  there  can  be  little  doubt  that  certain  of 
these  parasites  of  mosquitoes,  especially  those  with  trypaniform 
characters,  are  connected  with  some  Vertebrate  host,  just  as  are 
those  of  other  blood-sucking  Invertebrates.  At  the  same  time,  it  is 
also  probable  that  some  of  the  (typical)  Herpetomonads  found  (e.g. 
those  occurring  in  larvae,  such  as  Patton's  form,  also  certain  forms, 
described  by  the  Sergents)  are  simply  and  primarily  parasites  of 
the  Insect.  Lastly,  it  is,  of  course,  possible  that  such  a  parasite 
may  have  developed  a  trypaniform  condition  as  an  adaptation  to 
the  food  of  a  sanguivorous  Insect,  without,  however,  having  become 
able  to  live  in  the  Vertebrate  host ;  but  so  far  no  example  of  such 
a  case  is  definitely  known.  And  this  brings  us  to  the  subject  of 
the  derivation  of  the  Trypanosomes. 

(b)  Evolution  and  Phytogeny. 

It  must  be  fully  recognised  that  any  views  which  can  be  at 
present  advanced  upon  this  interesting,  but  very  puzzling  topic  are 
at  best  little  more  than  speculations.  Formerly  (I.e.),  the  writer 
inclined  to  the  idea  that  all  Haemoflagellates  are  to  be  derived  from 


forms  originally  parasitic  in  Invertebrates  ;  in  other  words,  the 
Invertebrate  was  regarded  as  the  primary  host,  the  Vertebrate  as 
the  secondary  or  intermediate  one.  We  now  think  this  view  was 
probably,  to  a  considerable  extent,  wrong ;  in  this  we  have  been 
mainly  influenced,  on  the  one  hand,  by  the  intestinal  Trypanoplas- 
mata,  and  on  the  other,  by  the  case  of  T.  grayi.  As  above  remarked, 
it  seems  evident  that  a  Vertebrate  is  the  primary  host  of  this  latter 
parasite  ;  and  the  same  would  follow,  by  inference,  for  the  other 
(Mammalian)  Trypanosomes  transmitted  by  Tsetse-flies.  Moreover, 
the  writer  thinks  he  did  not  allow  sufficient  weight  to  the  fact 
that  the  Invertebrates  which  harbour  Trypanosomes  are,  with  but 
few  exceptions,  blood-suckers.  For  these  reasons  we  are  now  inclined 
to  consider  most  of  the  Invertebrates  concerned  (e.g.  leeches,  many 
biting-flies,  etc.)  as  the  secondary,  intermediate  hosts  of  various 
Vertebrate  parasites  (probably  all  the  Piscine  and  Amphibian  ones, 
many,  but  perhaps  not  all  the  Mammalian  ones,  and  perhaps  some 
Avian  ones). 

The  only  important 1  exceptions  are  among  Insects ;  and  here 
it  is  quite  likely  that  we  have  both  primary  and  secondary  hosts. 
Besides  the  Tsetses,  Tabanids,  etc.,  the  common  house-fly  and 
related  genera,  in  which  Herpetomonads  (e.g.  H.  muscae-domesticae, 
H.  sarcophagae,  etc.)  occur,  ought  apparently  also  to  be  placed  in 
the  category  of  secondary  hosts.  For  Prowazek  (I.e.)  states 
that,  according  to  Brauer,  the  latter  flies  are  probably  de- 
scended from  blood-sucking  ones;  in  Avhich  case  their  parasites 
may  very  well  be  descended  from  haemal  forms,  which  are  now, 
perforce,  restricted  to  the  Invertebrate  host.  On  the  other  hand, 
there  are  several  instances  of  the  parasites  occurring  either  in  non- 
sanguivorous  Insects  or  in  forms  that  only  rarely  suck  blood, 
which  are,  we  think,  more  likely  cases  of  primary  parasitism. 
Among  these,  for  example,  are  H.  bombycis,  in  Bombyx  mori ;  H. 
gracilis,  in  larvae  of  Tanypus ;  Crithidia  campanulata,  in  larvae  of 
CMronomus  plumosus.  Lastly,  we  have  the  mosquitoes  and  their 
parasites,  both  of  imago  and  larva.  The  latter  is,  of  course, 
aquatic,  and  the  imago  is  by  no  means  limited  to  blood  for  nutri- 
ment. Having  regard  also  to  the  illustrative  series  of  transitional 
forms  between  the  monadine  type  and  the  trypaniform  one,  made 
known  by  Leger  and  others,  it  appears  to  us  that  here  as  well  the 
Insect  is  the  primary  host  of  the  various  Flagellates  concerned,  and 
that  where  these  are  connected  with  a  Vertebrate  host  the  latter  is 
to  be  regarded  as  the  secondary,  intermediate  one.  This  would 
apply  chiefly  to  certain  parasites  (e.g.  Trypanomorpha)  of  birds, 
though  not  necessarily,  it  is  to  be  noted,  to  all. 

Many  authorities  (such  as  Laveran  and  Mesnil,  Liihe,  Novy  and 

1  Herpetomonas  biitschlii  from  a  Nematode  (Trilobus)  and  the  curious  Trypano- 
phis  from  Siphonophores  do  not  appear  to  have  any  bearing  upon  this  question. 


M'Neal)  have  maintained  the  view  that  the  Invertebrate  is  the 
primary  host  in  all  cases.  Minchin,  however,  has  always  considered 
the  Vertebrate  as  the  principal  host ;  and  in  his  latest  memoir 
on  the  Trypanosomes  of  Tsetse-flies  (58),  proofs  of  which  he  very 
kindly  allowed  the  writer  to  see,  he  regards  all  Trypanosomes  as 
descended  from  an  intestinal  Vertebrate  form,  and  indicates  the 
lines  upon  which  the  evolution  may  be  supposed  to  have  advanced. 
This  ancestral  form  produced  resistant  cysts  for  dispersal,  and  thus 
contaminative  infection  was  brought  about.  (It  would  be  extremely 
interesting  to  ascertain  whether  the  intestinal  Trypanoplasmata 
known  (see  p.  249)  have  such  a  cyst-formation.)  The  next  stage  in 
evolution  is  when  the  parasite  has  penetrated  the  intestinal  wall, 
and  come  into  relation  with  the  circulatory  system.  Until  it  came 
into  relation  with  a  blood-sucking  Insect,  this  type  would  have  to 
pass  back  into  the  alimentary  canal  for  dissemination.  So  far,  we 
have  no  evidence  of  an  existing  instance  of  this  stage.  Subsequently, 
the  blood-parasite  became  adapted  to  an  Insectan  host,  in  the  gut 
of  which  it  encysted,  reinfection  of  the  Vertebrate  being  by  the 
contaminative  method.  T.  grayi  in  all  probability  furnishes  an 
example  of  this  type.  Lastly,  the  parasite  is  thoroughly  adapted 
to  the  biology  of  the  Insect  and  passes  forwards  to  the  front  part 
of  the  alimentary  canal :  infection  of  the  Vertebrate  is  now  by  the 
inoculative  method.  This  may  possibly  be  combined  in  some  cases 
with  the  contaminative  mode,  but  probably  in  most  encystment  no 
longer  takes  place,  being  unnecessary  (e.g.  the  lethal  Trypanosomes, 
Piscine  forms,  etc.). 

Of  course,  in  those  cases  where,  as  above  remarked,  the  Verte- 
brate is  probably  the  secondary  host,  there  is  no  reason  to  suppose 
that,  as  a  rule,  the  parasites  leave  the  circulatory  system. 

Phylogeny. — As  stated  at  the  beginning  of  this  article,  the 
Trypanosomes,  as  a  whole,  are  to  be  regarded  as  including  two 
entirely  distinct  families,  in  one  of  which  (the  Monadine  type)  the 
attached  flagellum  becomes  free  at  the  true  anterior  end,  and  in  the 
other  (the  Heteromastigine  type)  at  the  true  posterior  end.  The 
former  type  is  derived  by  the  progressive  migration  backwards  of  the 
kinetonucleus  towards  the  posterior  (aflagellar)  end,  in  the  manner 
well  illustrated  by  Leger's  series  of  Herpetomonadine  forms  (see 
Fig.  29).  The  latter  type  is  derivable  from  a  Trypanoplasmatine 
ancestor — itself  in  turn  doubtless  to  be  derived  from  a  fiodo-like 
form — by  the  loss  of  the  anterior  free  flagellum  ; l  so  that  the  non- 
flagellate  extremity  is  the  true  anterior  one. 

The  writer  is  unable,  owing  to  limits  of  space,  to  enter  fully 

1  A  comparison  of  the  different  degree  of  development  of  the  flagella  in  various 
forms  is  instructive  as  illustrating  the  manner  in  which  the  Trypauoplasmatine  condi- 
tion may  have  resulted  from  that  found  in  Bodo,  and  its  further  evolution. 


here  into  the  reasons  for  and  against  this  diphyletic  view,  which 
was  first  put  forward  by  Le"ger  (49).  A  complete  discussion  will 
be  found  in  his  Review  of  the  Haemoflagellates  (pp.  270-278). 
Liihe,  in  his  account  of  the  Haematozoa  in  Mense's  Handbuch  der 
Tropenkrankheiten  (2),  has  adopted  it,  though  on  somewhat  different 
lines  from  those  taken  by  us.  Minchin,  also,  has  expressed  the 
opinion  (Brit.  Mai.  Journ.,  1907,  ii.  p.  1320)  that  -  Trypanosomes 
are  most  likely  diphyletic.  On  the  other  hand,  many  authorities, 
including  Laveran  and  Mesnil,  hold  the  view  that  all  Trypanosomes 
are  descended  from  Herpetouionadine  ancestors,  basing  their  opinion 
on  the  resemblance  to  a  Herpetomonad  shown  by  many  Trypano- 
somes in  cultures,  and  by  young  individuals  of  T.  leivisi  (cf.  Fig.  20). 
In  many  cases,  at  any  rate,  we  regard  this  phase — as  we  have 
previously  said — rather  as  a  "  pseudo-Herpetomonadine  "  condition  ; 
and  in  such  cases  do  not  attribute  to  it  the  phylogenetic  importance 
which  is  done  by  some,  but  consider  it  to  be  probably  capable  of 
explanation  on  other  grounds  (see  I.e.}.  A  fact  which  seems  to  us 
of  considerable  significance  is  that  Trypanoplasmatine  forms  are 
known  to  occur  in  the  digestive  tract  of  fishes,  e.g.  "  Trypanoplasma  " 
intestinalis  in  Box  boops,  and  "  T."  rentriculi  in  Cydopterus  lumpus; 
moreover,  another  Heteromastigine  parasite  (Bodo  lacerfae)  is  found 
in  a  lizard.  On  the  other  hand,  no  indubitable  Herpetomonad  has 
yet  been  described  from  the  alimentary  canal  of  a  Vertebrate,  which 
we  may  assume  to  have  been  the  original  habitat  of  the  primitively 
Vertebrate  parasites. 

Hence,  all  things  considered,  we  come  to  the  general  conclusion 
that  the  Trypanosomes  which  have  the  Vertebrate  for  their  primary 
host  are  Heteromastigine  forms  ;  those  derived  from  primitively 
Invertebrate  parasites,  on  the  other  hand,  are  probably  Monadinc 
forms.  Endeavouring  to  use  this  view  practically,  for  purposes  of 
classification,  or,  at  any  rate,  of  convenient  partition  of  the  Trypano- 
somes, we  have  as  follows  :  —  The  parasites  of  fishes  belong  to  the 
Heteromastigine  type ;  this  can  be  said  with  some  degree  of 
confidence,  in  spite  of  the  "  Crithidial "  forms  assumed  by  the 
parasites  in  leeches.  Probably  the  same  is  true  also  of  most  forms 
of  cold-blooded  Vertebrates.  Of  the  Avian  ones,  on  the  contrary, 
some  at  any  rate  (e.g.  those  of  the  type  of  Trypanomorpha  noctuae) 
are  Herpetomonadine  forms.  Among  Mammalian  parasites  the 
various  lethal  Trypanosomes  (e.g.  T.  brucii,  etc.)  are  to  be  regarded 
as  Heteromastigine  forms.  We  will  only  mention  in  passing  that 
certain  movements  of  these  forms  in  the  living  blood  (cf.  p.  217) 
suggest  very  forcibly  that  the  aflagellar  end  is  the  true  anterior 
extremity.  Of  the  other  known  (accustomed)  parasites  of  Mammals, 
whose  number  has  considerably  increased  of  late,  it  is  quite  possible 
that  some  (e.g.  those  of  bats,  which  may  have,  perhaps,  mosquitoes 
as  their  alternate  hosts)  are  Herpetomonadine  forms. 



The  reasons  for  the  division  of  the  Trypanosomes  into  two 
distinct  families  have  been  alluded  to  in  the  previous  section. 
Besides  the  fundamental  diagnostic  characters,  namely,  the  true 
orientation  of  the  body  and  the  biological  features  associated  there- 
with, it  is  quite  likely  that  important  differences  in  regard  to  the 
life-cycle  will  become  evident  as  our  knowledge  increases. 


Family  TRYPANOMORPHIDAE,  Woodcock.  —  Haemoflagellates 
derived  from  a  uniflagellate,  Herpetomonadine  form,  in  which  the 
point  of  insertion  of  the  flagellum  into  the  body  has  travelled  back- 
wards from  the  anterior  end  for  a  considerable  distance,  the 
flagellum  itself  having  become,  concurrently,  attached  to  the  body 
for  part  of  its  length  by  means  of  an  undulating  membrane.  At 
present  only  one  genus  is  distinguished. 

Genus  Trypanomorpha,  Woodcock.  With  the  characters  of  the 
family.  The  genus  was  founded  for  Schaudinn's  Avian  parasite, 
Trypanosoma  (Halteridium)  noduae  (Celli  and  San  Felice),1  from 
Athene  noctua  and  Culex  pipiens.  As  above  mentioned,  it  is  probable 
that  other  Avian  forms,  and  perhaps  some  Mammalian  ones,  will  be 
found  to  agree  with  this  generic  type  ;  at  present,  however,  it  is 
not  possible  to  say  which  with  any  certainty,  and  hence  they  are 
retained  under  the  heading  "  Trypanosoma." 

Reference  has  been  made  to  the  possibility  of  Leger's  Crithidia 
fasciculata  from  Anopheles  maculipennis,  and  other  Insectari  parasites 
which  show  marked  trypaniform  characters,  being  also  really 
Haemoflagellates.  In  such  a  case  the  genus  Trypanomorpha  may 
prove  to  be  synonymous  with  Crithidia ;  if  so,  the  latter  name  will 
take  priority.  Ltihe,  it  is  to  be  noted,  in  his  account  of  the 
Haematozoa  (I.e.),  regards  all  the  Trypanosomes  of  Mammalia  as 
belonging  to  the  Herpetomonadine  type,  and  has  proposed  the  new 
generic  name  Trypanozoon  for  these  forms. 


Family  TRYPANOSOMATIDAE,  Doflein.  —  Flagellates,  with  but 
few  exceptions  haemal  parasites,  derived  from  a  bi flagellate,  Bodo- 
like  type,  in  which  the  posteriorly  directed  (trailing)  flagellum  is 
always  present  and  attached  to  the  side  of  the  body  by  an  undu- 
lating membrane,  of  which  it  constitutes  the  thickened  border. 

1  Schaudinn  placed  this  form  in  the  genus  Trypanosoma.  We  incline,  however, 
to  the  view  that  the  type-species  of  that  genus  (T.  rotatorium)  is  a  Heteromastigine 
type,  and  therefore  restrict  that  genus  to  such  forms. 



The  other,  the  anterior  flagellum,   may   or  may  not  persist.      At 
least  three  genera  known  so  far. 

Genus  Trypanoplasma,  Laveran  and  Mesnil.  The  anterior 
flagellum  is  present. 

Type-species,  T.  borreli,  Lav.  and  Mesn.  (Fig.  11).  Length  of  body 
20-22  /*,  of  free  flagella  13-15  /x,  breadth  3^-4^  p..  Parasitic  in  Leuciscus 
erythrophthalmus,  rudd,  and  Phoxinus  laevis,  minnow.  Other  species  are  T. 
cyprini,  from  the  carp,  and  T.  varium,  a  rather  larger  form,  from  the  loach. 

Genus  Trypanophis,  Keysselitz.  The  anterior  flagellum  is  pre- 
sent. The  free  part  of  the  posterior  flagellum  is  short,  and  the 
undulating  membrane  is  straight  and  relatively  narrow.  The 
species  for  which  this  genus  was  founded  is  parasitic  in  certain 
Siphonophores,  and  almost  certainly  not  a  haemal  form. 

e.C,  - 

Fit;.  30. 

Trypanophis  grcitjbeni  (Poche).  e.c,  ectoplasmic  cap;  e.l,  delicate  ectoplasmic  layer,  thin- 
ning out  posteriorly  ;  i,  inclusions  in  the  cytoplasm  ;  x,  nuclear  body  of  uncertain  origin  and 
significance.  (After  Keysselitz.) 

Type-species,  T.  yrobbeni  (Poche).  Average  length  60-65  //,,  width 
about  4  p..  From  Cucubalus  kochii,  Halistemma  teryestinum,  Monophyes 
gracilis,  Gulf  of  Trieste.  Apparently  the  same  parasite  has  also  been 
observed  in  Abyla  pentagona,  Gulf  of  Naples.  The  organisms  are  to  be 
found  in  all  the  ramifications  of  the  coelenteron,  from  the  digestive-cavity 
of  the  gastrozoids  to  the  radial  canals  of  the  medusoid  buds.  Nothing 
is  known  with  regard  to  the  transmission  from  one  Siphonophoran  colony 
to  another. 

Great  interest  attaches  to  certain  Trypanoplasmatine  parasites 
recently  described  from  the  alimentary  canal  of  fishes.  In  their 
general  morphology  and  the  possession  of  an  undulating  membrane 
they  agree  closely  with  Trypanoplasma,  and  their  describers  have 
included  them  in  this  genus,  as  T.  intestinalis,  L6ger,  and  T.  ven- 



triculi,  Keysselitz.     So  far  as  those  points  are  concerned,  however, 

they  agree  also  with  the  above-mentioned  genus  Trypanophis  (cf. 

Figs.  30  and  31).  Indeed,  Leger,  in  his  account  of  T.  intestinalis, 
commenting  on  the  great  resemblance  of  this 
parasite  to  Trypanophis,  suggested  that  the  latter 
form  might  be  included  in  Trypanoplasma.  We 
consider  that  Trypanophis  grobbeni,  on  account 
of  its  curious  habitat  and  somewhat  peculiar 
nature,  should  certainly  be  kept  distinct.  More- 
over, as  regards  the  intestinal  Trypanoplasma- 
tine  forms,  the  fact  that  they  are  most  likely 
not  haemal  parasites  renders  it  very  probable 
that  their  life-cycle  differs  in  many  ways  from 
that  of  the  ~b\ood-Trypanoplasmata  (cf.  the  hypo- 
thetical stages  in  evolution  outlined  above, 
p.  246).  Formerly,  we  placed  "  T."  intestinalis 
with  Trypanophis  on  these  grounds  ;  but  it  seems 
preferable  to  consider  it  as  belonging  to  an 

down  the  side  near  the  independent  genus,  along  with  "  T"  ventriculL 

undulating-membrane  (cf. 

in  B  the  As  we  are  averse  to  the  practice  of  instituting 

;ti   /-irt-1-iV.ift  -1-  " 

FIG.  31. 

"  Trypanoplasma  "  in- 
testinalis. In  A  a  row  of 
spherules  is  seen  running 

kinetonucleus  is  double.  .  .  , 

(After  an  original  draw-  new  genera  in  a  treatise,  we  do  riot  propose  to 

Lege^f^  ^  ^  ^    d°  SO  here- 

Before  leaving  this  point,  it  may  be  noted 

that,  in  the  case  of  these  Heteromastigine  forms,  the  presence  of 
an  undulating  membrane  and  consequent  trypaniform  appearance 
does  not  bear  the  same  relation  to  a  haemal  habitat  as  seems  to 
be  the  case  in  the  Monadine  types.  As  Doflein  has  already  pointed 
out,1  the  undulating-membrane,  in  the  Trypanoplasmatine  parasites, 
has  doubtless  been  developed  as  the  result  of  the  contiguity  of  the 
trailing  flagellum  of  the  Bodonine  type  to  the  side  of  the  body  ; 
a  quite  different  origin  from  that  in  the  other  section.  Hence  this 
condition  is  more  or  less  independent  of  the  habitat  of  these  forms. 
Genus  Trypanosoma,  Gruby  (principal  synonyms : 2  Undulina, 
Lank.,  1871  ;  Herpetomonas,  Kent,  1880,  but  only  in  part,  since 
the  type-species  is  H.  muscae-domesticae ;  Paramoecioides,  Grassi, 
1881;  Haematomonas,  Mitrophan.,  1883;  Trypanomonas,  Danil., 
1885,  for  young  forms).  There  is  no  anterior  flagellum.  The 
point  of  insertion  of  the  attached  (posterior)  flagellum  into  the 
body,  and,  consequently,  the  commencement  of  the  membrane,  may 
be  anywhere  in  the  anterior  half  of  the  body,  but  is  usually  near 
the  extremity.3 

1  Die   Protozoen   als   Parasiten  und   Kranklieitserreger   (Fischer,  Jena,    1901), 
p.  54. 

2  For  remarks  on  the  synonymy  of  this  genus,  readers  are  referred  to  the  writer's 
previous  article  (p.  287). 

3  The  type-species  is  T.  rotatorium,  Mayer,  of  frogs.     At  present,  unfortunately, 
this  parasite  cannot  with  certainty  be  included  in  the  above  diagnosis,  owing  to  its 



The  sub-classification  of  this  genus,  or  rather  the  grouping  and 
arrangement  of  the  numerous  Trypanosomes  at  present  included  in 
it,  is  a  question  of  great  difficulty  and  one  in  regard  to  which 
hardly  anything  has  been  done  as  yet.1  This  is  chiefly  owing  to  the 
fact  that  so  little  is  still  known  of  the  life-history  of  most  that 
hitherto  any  attempt  to  group  the  parasites  has  been  dependent  upon 
their  adult  morphology.  This  is  not  a  very  satisfactory  criterion, 
since,  as  we  have  seen,  on  the  one  hand,  the  differences  in  this 
respect  between  different  forms  may  be  very  slight ;  and  on  the 
other,  a  particular  parasite  may  itself  vary  very  greatly  at  different 
times  and  under  different  conditions  (see  under  "  Morphology  "). 
Moreover,  it  may  very  well  be  that  as  more  life-histories  come  to  be 
revealed,  some  of  the  forms  at  present  placed  for  convenience  in 

FIG.  32. 

A,  Tri/iKuwsoma  gamliiense  (from  the  blood),  after  Bruce  and  Labarro  ;  B,  T.  equinum,  after 
Lignieres  ;  C,  T.  evansi,  from  an  original  drawing  ;  D,  T.  cquiperdum,  after  Lign. 

the  genus  Trypanosoma  will  have  to  be  transferred  to  new  ones 
(as  an  example  may  be  mentioned  T.  grai/i). 

For  the  present,  at  any  rate,  a  very  useful  aid  towards  dis- 
tinguishing different  species  is  furnished  by  the  biological  relations 
of  the  parasites.  For  it  may  be  assumed  that  here,  as  is  usual 
among  the  Sporozoa,  a  particular  species  is,  in  general,  restricted 
either  to  one  particular  host,  or,  at  most,  to  a  few  allied  ones. 
Difficulty  arises  in  considering  the  Mammalian  forms,  many  of 
which  have  never  been  observed  in  the  true,  natural  hosts,  but  only 

unusual  shape,  position  of  kinetonucleus,  etc.  The  occurrence,  however,  of  an 
allied  form  in  Hyla,  which  is  evidently  intermediate  between  T.  rotatorinm  and 
the  more  typical,  fusiform  species,  suggests  that  the  former  also  belongs  to  the  Hetero- 
mastigine  section. 

1  Koch,  however,  has  attempted  a  classification  of  the  Mammalian  forms,  which  he 
arranges  in  two  groups,  the  first  including  such  different  forms  as  T.  lewisi  and  the 
large  T.  theileri  of  cattle  ;  the  other,  most  of  the  lethal  forms,  which  he  considers 
are  not  distinct  species.  This  arrangement  is  very  artificial  and  has  nothing  to 
recommend  it. 



in  various  unaccustomed  animals,  for  which  they  are  more  or  less 
lethal.  The  important  immunisation  experiments  first  carried  out 
by  Laveran  and  Mesnil,  and  since  then  by  other  workers,  have 
shown,  however,  that  several  of  the  parasites  causing  the  different 
trypanosomoses  now  known  are  distinct  species.  • 

A  full  description  of  all  the  known  forms  and  tlieir  characteristics  is 
impossible  within  the  limits  of  this  article.  It  must  suffice  to  mention 
some  of  the  more  important  and  better-known  parasites,  arranged  under 
the  different  classes  of  Vetebrate  hosts  ;  for  fuller  details  regarding  them, 
reference  should  be  made  to  the  writer's  previous  account,  or  to  Nabarro's 
revised  edition  of  Laveran  and  Mesnil's  treatise,  which  is  most  useful  in 




FIG.  33. 
A  and  B,  T.  theileri;  C-E,  T.  "transwalien*:."     x  1250.    (After  L.  and  M.) 

this  connection.      A  list  of  known  hosts  and  their  Trypanosomes  is  given 
at  the  end  of  this  chapter. 

(a)  Parasitic  in  Mammals.  Trypanosoma  lewisi,  Kent,  the  common 
natural  parasite  of  rats  (Figs.  7,  A  ;  20,  A).  Length  *  24-25  p.,  breadth 
l|-2  p..  This  species  is  characterised  by  its  narrow  and  pointed  aflagellar 
extremity,  and  by  the  position  of  the  trophonucleus  in  the  flagellar  half 
or  third  of  the  body.  The  cytoplasm  is  usually  free  from  granules.  T. 
Irudi,  Plitnmer  and  Bradford.  Length  28-30  p.,  breadth  2-2|  //.  The 
anterior  end  is  usually  bluntly  rounded  (Figs.  7,  B  ;  17,  A).  The  cytoplasm 
often  contains  granules  in  the  posterior  half.  Natural  hosts  probably 
various  Antilopidae  (e.g.  gnu,  "  koodoo,"  etc.),  and  buffaloes.  The  cause  of 
Nagana  or  Tsetse-fly  disease  in  cattle,  horses,  etc.,  in  South  Africa.  T. 
gambiense,  Button  (Syn.  T.  ngandense,  Castell).  Length  21-23  fj.,  breadth 
1^-2  /JL.  This  species  (Fig.  32,  A),  according  to  its  average  size,  is  one  of 
the  smallest  known.  The  cause  of  human  trypanosomosis  in  West  and 

1  The  dimensions  given  are  intended  to  indicate  the  average  size  of  the  parasite  in 
each  case,  but  can  only  be  considered  as  approximate.  The  length  is  inclusive  of  the 
flagellum,  unless  otherwise  stated. 


Central  Africa.  The  earlier  stages  of  the  disease,  when  the  parasites  are 
confined  to  the  blood,  are  known  as  Trypanosoma-k\er  ;  the  later  ones,  after 
the  organisms  have  penetrated  into  the  cerebro-spinal  canal,  constitute  the 
deadly  malady  of  sleeping-sickness.  The  true,  natural  host  is  unknown. 
T.  equinum,  Voges  (Syn.  T.  elmassiani,  Lign.).  Length  22-25  p,  width 
1^-2  /j..  Distinguished  from  all  other  forms  by  the  minute  size  of  the 
kinetonucleus  (Fig.  32,  B).  Hydrochoerus  capybara  is  almost  certainly  a 
natural  host.  Other  well-known  lethal  parasites  are  :  T.  evansi  (Steel),  of 
Surra  in  horses  in  Indo-Burmah  (Fig.  32,  c)  ;  T.  eqiiiperdum,  Doflein  (Syn. 
T.  rouyeti,  Lav.),  the  cause  of  Dourine  in  horses,  transmitted  naturally  by 
coitus  (Fig.  32,  D)  ;  T.  theileri,  Laveran,  a  very  large  form,  often  surpassing 
50  p.  in  length,  which  causes  "bile-sickness"  of  cattle  in  the  Transvaal 
(T.  transvaaliense,  Lav.,  with  the  kinetonucleus  near  the  middle  of  the 

FIG.  34. 

T.  johnstoni.  g,  deeply-staining  granule  at 
distal  extremity  of  flagellar  border,  x  1500. 
(After  Dutton  and  Todd.) 

Fl°-  35. 

A  Trypanosome  from  Sene- 
gambian  birds,  x  150C.  (After 
D.  and  T.) 

body  (Fig.  33,  C-E),  has  been  shown  to 
be,  in  all  probability,  only  a  phase  of 
T.  theileri)  ;  and  T.  dimorphon,  Dutt. 
and  Todd,  which  gives  rise  to  a  trypano- 
somosis  of  horses  in  Senegambia. 

(6)  Parasitic  in  birds.  T.  avium, 
Danil.,  Lav.  emend.,  probably  the  form 
to  which  Danilewsky's  original  investi- 
gations related,  occurring  in  owls  and, 
according  to  Novy  and  M'Neal,  in 
various  other  birds.  Length  35-45  />t 
(Fig.  7,  F).  T.  johnstoni,  Dutt.  and 

Todd.  Length  36-38  //.,  width  1^-  p.. 
TVn«  -nnrnsitp  in  <5O  «lpnrlpr  i<5  'iltnnst- 

llns  parasite   is  so  i    as   almost 

to   justify   the  description   spirochaeti- 

form    (Fig.    34).      From   Estrelda.      The   opposite   extreme    of   form    is 

seen   in   a   Trypanosome,   T.  hannae,   Pittaluga,  originally  described   by 

Hanna    (25)    from    an    Indian    pigeon    (Fig.    7,    o)  ;    this    is    relatively 

very  broad,  and  has,  moreover,  a  long,  attenuated  aflagellar  extremity,  the 

latter  character  being  not  unusual  in  bird-Trypanosomes.     On  the  other 

FIG.  30. 

T.  paddae.  At  x  the  base  of  the  flagel- 
lum  is  thickened  prior  to  division. 
X  1200.  (After  Thiroux.) 



hand,  Button  and  Todd  have  described  a  wide  form  from  Senegambian 
birds,  which  has  this  end  bluntly  rounded,  giving  the  parasite  a  stumpy 
appearance  (Fig.  35).  It  is  interesting  to  note  that  this  Trypanosome 
occurred  in  the  same  birds  (Estrelda)  in  which  the  very  different  T.johnstoni 
was  found.  T.  paddae  (Fig.  36),  from  the  Java  sparrow,  has  been  studied 
by  Thiroux  (83),  and  apparently  lends  itself  to  cultivation  and  inoculation 
into  other  birds  as  readily  as  do  many  Mammalian  forms.  Finally,  there 
is  the  remarkable  parasite,  "  T."  (Spirochaeta)  ziemanni,  described  by 
Schaudinn.  If  this  form  is  really  a  Trypanosome,  it  certainly  belongs 
to  the  Heteromastigine  section,  and  may  for  the  present  be  placed  in  the 
genus  Trypanosoma.  But  it  may  be,  after  all,  a  true  Spirochaete,  and 
belong  to  the  Bacteria  (cf.  footnote,  p.  237). 

(c)  Reptilian  forms.      Scarcely  any  Trypanosomes  have  been  observed 
in  Reptiles.      The  only  one  which  has  been  figured  is  T.  damoniae,  Lav. 
and  Mesn.      Length  32  /A,  breadth  4  //,.     The  general  structure  (Fig.  7,  j) 
presents  nothing  unusual.      As  in  Piscine  forms,  the  body  is  often  rolled 
up  on  itself.      From  Damonia  reevesii,  a  tortoise.     Another  form  (T.  boueti), 
lately  described  from  a  lizard,  is  said  to  resemble  the  flat,  smooth  type 
of  T.  rotatorium  (below). 

(d)  Parasitic  in  Amphibian  hosts.     The  Trypanosomes  of  frogs  show 
a  remarkable  variation  in  form,  size,  and  appearance,  and  it  is  not  at  all 
certain,  in  some  cases,  how  far  this  is  due  to  polymorphism,  and  how  far 
to  distinct  species  being  concerned.      The  type-species  of  the  genus  is  T. 
rotatorium  (Mayer).      (Synn.  Amoeba  rotatoria  and  Paramoecium  costatum 
or  loricatum,   Mayer,  July   1843  ;  Trypanosoma  sanyuinis,   Gruby,  Nov. 

1843  ;  Undulina  ranarum,  Lank., 
1871.)  Laveran  and  Mesnil  have 
worked  on  this  form  and  dis- 
tinguish two  principal  types,  one 
having  the  surface  of  the  body 
thrown  into  parallel  ridges  (Figs. 
8,  B  ;  37,  A),  the  other  having  a 
smooth,  regular  surface  (Figs.  8,  A  ; 
37,  B).  The  parasites  are  very 
large,  being  40-60  //,  in  length,  by 
from  5-40  p.  in  width  ;  the  two 
dimensions  vary  more  or  less  in- 
versely. The  great  variation  in 
shape  of  the  body  and  of  the 
anterior  end  is  seen  from  the 
figures.  The  kinetonucleus  is 
aisually  situated  some  distance  from  the  non-flagellate  or  anterior  extremity, 
.and  may  be  quite  close  to  the  trophonucleus  ;  sometimes,  however,  it  is 
fairly  near  the  end.  Chiefly  for  this  reason,  Franca  and  Athias  (22) 
split  up  the  species  into  two,  T.  costatum  or  loricatum  (Mayer),  with  the 
kinetonucleus  near  the  centre,  and  T.  rotatorium,  with  it  near  the  end. 
As  the  position  of  this  organella  is  very  variable  and  intermediate  stages 
occur,  we  do  not  think  anything  is  gained  by  doing  this,  at  present. 
-Similarly,  the  validity  of  two  new  species  which  Franca  and  Athias 

FIG.  37. 

T.  rotatorium  (Mayer).    Bibbed  and  smooth 
forms,     x  1000  (approx.).    (After  L.  and  M.) 



create,  namely,  T.  undulans  and  T.  elegans,  is  somewhat  doubtful.  Button 
and  Todd  have  described  two  very  long  forms  from  Gambian  frogs,  which 
they  have  named  T.  mega  and  T.  karyozeukton ;  these  forms  exhibit 
peculiarities  in  the  cytoplasm  (see  p.  212),  and  in  the  latter  parasite  a 
chain  of  chromatic  granules  runs  from  one  nucleus  to  the  other  (Fig.  8,  D). 
A  type  which  is  certainly  distinct  is  T.  inopinatum,  Sergent,  from  the 
edible  frog.  This  parasite  (Fig.  8,  c)  is  slender  (25-30  /z  by  3  //,),  and 
resembles  a  Mammalian  or  Piscine  form.  Another  well-characterised 
species  is  T.  nelspruitense,  Lav.,  in  which  the  body  is  very  vermiform  and 
the  free  flagellum  very  long  (Fig.  8,  E). 

(e)  Forms  parasitic  in  fishes.  Trypanosomes  occur  very  frequently 
in  fishes,  and  a  great  many  species  have  been  described.  T.  remuki, 
Lav.  and  Mesn.  This  para- 
site occupies  about  the  same 
position  among  Piscine  Try- 
panosomes as  does  T.  lewisi 
among  Mammalian  ones.  It 
is  a  slender  form,  with  taper- 
ing, pointed  extremities.  The 
trophonucleus  is  in  the  pos- 
terior half  of  the  body.  Para- 
sitic in  Esox  lucius,  the  pike. 
Laveran  and  Mesnil  have  dis- 
tinguished two  varieties,  based 
upon  the  considerable  differences  in  size  met  with,  namely,  var.  parra, 
medium  length  30  /x,  of  free  flagellum  10-12  /JL,  with  breadth  1^-2  p. ;  and 
var.  magna  (Fig.  8,  L),  minimum  length  45  /x,  of  which  17-20  /A  is  for  the 
flagellum,  and  breadth  2-2J  //,.  T.  cobitis  and  T.  carassii  (Mitrophanow) 
were  among  the  first  Piscine  forms  to  be  described,  and  probably  corre- 
spond to  many  of  those  seen  by  Danilewsky.  T.  granulosum  of  the  eel 
is  a  remarkably  long,  eel-like  form  (Fig.  8,  K),  70-80  //.  by  2|-3  p.  The 
kinetonucleus  is  relatively  very  large,  as  is  often  the  case  in  Piscine  forms, 
and  close  to  the  anterior  end,  which  is  sharply  acute.  Several  forms 
have  been  observed  in  flat-fish,  certain  of  which  (e.g.  T.  flesi,  Lebailly) 
belong  to  a  different  type,  being  relatively  wide,  with  only  a  short 
flagellum.  From  Elasmobranchs,  two  very  large  forms  (T.  scyllii  and 
T.  raiae)  have  been  described  by  Laveran  and  Mesnil ;  these  attain  a 
length  of  70-80  yit,  and  usually  have  the  body  coiled  up  on  itself  (Fig. 

FIG.  38. 

A,  T.  scyllii ;  B,  T.  raiae.     x  1200. 
(After  L.  and  M.) 



Although  these  remarkable  bodies  have  not  been  shown  yet  to 
possess  an  actual  trypaniform  structure,  the  fact  that  they  are  known 
to  give  rise  to  Flagellate  phases  of  very  Herpetomonadine  character 
points  so  conclusively  to  their  connection  with  that  type  of  parasitic 
Flagellate,  and  is  of  such  importance  as  proving  that  a  parasitic  Flagellate 


can  and  does  become  intracellular  in  the  Vertebrate  host,  that  a  brief 
consideration  of  them  is  essential  to  the  completeness  of  this  article. 

The  Leishman- Donovan  bodies  are  constantly  found  in  certain 
tropical  fevers  (such  as  Dum-dum  fever,  Kala-Azar),  particularly  pre- 
valent throughout  Indo-Burmah,  of  which  they  are  now  generally  admitted 
to  be  the  cause.  These  parasites  were  discovered  by  Leishmau  in  1900, 
but  before  his  first  account  of  them  was  published  (91)  they  were  also  seen 
independently  by  Donovan.  Moreover,  organisms  very  similar  to  these 
parasites  (indeed,  morphologically,  the  two  kinds  are  hardly  distinguish- 
able) are  found  in  various  sores  or  ulcers  (known  as  Delhi  boil,  Oriental 
sore,  "  bouton  d'Alep  "),  to  which  people  in  different  parts  of  the  tropics 
are  liable.  The  latter  were  first  clearly  recognised  and  described  by 
Wright  (97). 

In  the  former  type  of  disease,  there  is  a  general  systemic  infection, 
the  parasites  spreading  to  all  parts  of  the  body,  and  being  met  with  in 
the  spleen,  where  they  are  usually  very  abundant,  liver,  bone-marrow, 
and  (more  rarely)  in  the  peripheral  circulation.  The  latter  type  of 
disease,  on  the  other  hand,  is  one  of  localised  infection,  the  organisms 
being  restricted  to  the  neighbourhood  of  the  skin  lesions  ;  and  in  this 
case  the  parasites  never  seem  to  become  distributed  throughout  the  body, 
producing  a  systemic  infection.  For  this  reason,  though  the  organisms 
in  the  two  cases  seem  to  be  undoubtedly  closely  related,  they  are  probably 
specifically  distinct.  In  the  Vertebrate  host,  the  parasites  are  generally 
intracellular.  Free  forms  are  met  with,  doubtless  liberated  by  the  break-up 
of  the  host-cells,  but  these  probably  soon  invade  fresh  cells.  Leish man's 
form  is  parasitic  in  large  uninuclear  leucocytes  (Fig.  39,  II),  and  especially 
in  cells  of  the  vascular  endothelium,  which  are  often  packed  with  the 
little  bodies,  becoming  greatly  distended  (as  macrophages).  According  to 
both  Donovan  (88)  and  Laveran  and  Mesnil  (90),  the  parasites  also 
occur  in  the  red  blood-corpuscles.  Wright's  form  occurs  in  the  ulcer 
cells,  and  in  large  migratory  corpuscles  (phagocytes)  of  the  granulation- 

The  parasites  themselves  are  very  minute,  and  usually  ovoid  or 
pyriform  in  shape,  the  latter  being  perhaps  the  more  typical.  The 
splenic  form  is  somewhat  smaller  than  the  localised  type,  being  3|-4  p, 
in  length  by  l|-2  p.  in  width  (39,  I),  while  Wright's  form  is  about  4  fj. 
by  3  //,  (39,  III).  The  cytoplasm  is  finely  granular  and  fairly  uniform 
in  character ;  but  sometimes  it  is  vacuolated.  The  most  interesting 
point  about  the  morphology  is  the  fact  that  two  chromatic  bodies,  of  very 
unequal  size,  are  invariably  to  be  recognised.  The  larger  nuclear  body, 
which  corresponds  to  the  trophonucleus  of  an  ordinary  Haemoflagellate, 
is  usually  round  or  oval ;  the  smaller  one,  representing  a  kinetonucleus, 
has  the  form  either  of  a  little  rod  or  of  a  round  grain,  and  stains  very 
deeply.  The  two  nuclei  are  generally  quite  separate,  but  sometimes  they 
appear  to  be  connected.  The  organisms  multiply  in  two  ways :  (a)  by 
binary  fission,  and  (6)  by  multiple  division  or  segmentation.  The  chief 
stages  in  the  first  method  are  well  known  (Fig.  39,  I,  6)  ;  they  offer  great 
resemblance  to  the  corresponding  process  in  Piroplasma.  Multiple  division 
has  not  yet  been  so  satisfactorily  made  out.  It  appears  to  conform  more 



or  less  to  the  radial  or  rosette  type  of  multiplication  (I,  c),  enlarged 
rounded  parasites,  with  a  varying  number  of  nuclei  (up  to  about  10) 
uniformly  arranged  near  the  periphery,  having  been  often  noticed.  The 
details  are,  however,  rather  differently  described  by  different  workers. 

Our  knowledge  of  any  further  development  undergone  by  these 
parasites  is  limited  at  present  to  the  Leishman-Donovan  bodies,  and  is 
due  in  the  first  instance  to  Rogers  (94).  Rogers  cultivated  the  parasites 



F/o.  39. 

I,  Leishmania  (Piroplasmu)  donovani  (Lav.  and  Mesn.).  a,  typical  pear-shaped  or  oval  forms  ; 
6,  various  stages  in  binary  fission  ;  c,  nuclear  division,  preparatory  to  multiple  fission  ;  d,  Rndo- 
corpuscular  forms  in  red  blood-corpuscles  (p,  pigment  grains)  ;  e,  bacillary  form  of  the  parasite 
in  a  corpuscle  ;  M,  large  macrophageal  cell  with  many  parasites.  (After  Donovan.)  II,  Uni- 
nuclear leucocyte  (L)  containing  several  parasites.  (After  L.  and  M.)  Ill,  L.  (P.,  Helcosama) 
troj>i<-<i  (Wright),  a,  single  individuals  ;  b,  dividing  forms.  (From  Mesnil,  mostly  after  Wright.) 
IV,  L.  (P.)donocani  in  cultures  of  different  ages,  a,  ordinary  forms  of  varying  size  ;  6,  c,  stages 
in  multiple  division  ;  e,  /,  and  g,  flagellate  forms.  (After  Rogers.) 

in  citrated  blood,  at  a  lower  temperature,  and  made  the  astonishing 
discovery  that  Flagellate  forms  were  developed  from  them.  This  result 
has  since  been  fully  corroborated  and  further  details  ascertained  by  Christo- 
phers (87),  Leishman  and  Statham  (92),  and  others.  Different  stages 
in  the  process  are  seen  in  Fig.  39,  IV,  d-g  ;  and  Fig.  40.  The  parasites 
increase  greatly  in  size  and  become  vacuolated  (this  is  probably  due  to 
the  artificial  medium  in  which  they  are).  Multiplication  by  binary  fission 
takes  place,  and  with  successive  generations  the  shape  of  the  body  alters  ; 
from  being  pyriform  it  passes  through  a  fusiform  condition,  and  finally 
becomes  elongated  and  slender.  Meanwhile,  in  many  of  these  phases,  a 




flagellum  has  made   its   appearance  ;    when  this  is  fully  developed  the 
parasite  quite  resembles  an  ordinary  Herpetomonas. 

The  origin  of  the  flagellum  is  interesting.  A  distinctive  vacuole-like 
structure  arises  near  the  end  which  will  become  the  flagellar  end,  in  close 
connection  with  the  kinetonucleus — a  point,  probably,  of  importance. 
This  vacuole  increases  and  suddenly  is  ruptured,  some  of  its  contents 
being  extruded  to  the  exterior  as  a  tuft  or  fringe  of  pink -staining 
substance.  In  the  middle  of  this,  a  small  flagellum  is  seen,  but  how 
exactly  it  is  formed  is  not  known.  Once  constituted,  the  flagellum  grows 
rapidly.  Even  in  the  most  fully-developed  Flagellate  phases,  however, 
in  no  case  has  anything  comparable  to  an  undulating-membrane  been 
observed.  The  kinetonucleus  is  comparatively  near  one  end  of  the  body, 


FIG.  40. 

Stages  in  the  development  of  the  flagellated  form.  (From  Leishman.)  1,  ordinary  spleen 
parasite ;  2,  3,  growth  and  vaeuolisation  in  cultivation ;  4,  5,  appearance  and  growth  of  the 
special  "  flagellar  vacuole,"  close  to  the  kinetonucleus  ;  6,  rupture  of  this  vacuole  and  protrusion 
of  a  tuft  of  pink-staining  threads  ;  7,  growth  of  the  flagellum,  its  base  being  inserted  in  the 
collapsed  vacuole  ;  8,  acquirement  of  the  Herpetomonad  form. 

and  the  flagellum  springs  directly  from  that  end,  not  being  actually 
connected,  apparently,  with  the  former  organella. 

Another  remarkable  process  observed  in  these  developmental  forms  in 
cultures  is  unequal  longitudinal  fission.  Very  thin,  sickle-like  ("  spirillar  ") 
portions  of  the  body  are  split  off  from  one  side  of  a  parent-individual. 
More  than  one  of  these  thread-like  forms  may  be  successively  cut  off.  The 
unusual  feature  of  the  process  is  that  neither  the  two  principal  nuclear 
elements  nor  the  flagellum  take  part  in  it.  Subsequently,  these  fission 
forms  seem  to  give  rise  to  very  slender  flagellar  ones.  To  what  extent 
this  represents  a  normal  (natural)  mode  of  multiplication  is  uncertain. 

No  other  stages  have  been  observed  in  cultures,  and  the  organisms 
degenerate  and  ultimately  die  off.  The  above  facts  demonstrated,  how- 
ever, that  the  Leishman-Donovan  bodies  can  undergo  important  changes 
outside  the  human  host,  and  rendered  it  probable  that  they  do  so 
naturally,  though  whether  in  the  free  condition  or  in  an  alternate  host 
was,  until  lately,  quite  unknown.  The  superficial  position  of  the  localised 
form  (Wright's  type)  points  very  strongly  to  infection  by  means  of  some 
biting  Insect,  and  it  is  natural  to  infer  that  the  same  holds  also  for  the 


splenic  type,  when  its  occurrence  in  the  circulation  is  borne  in  mind. 
Here,  again,  Kogers  gave  the  lead.  This  worker,  finding  that  the  parasites 
developed  flagellar  stages  most  readily  in  an  acid  medium,  suggested  (95) 
that  the  stomach  of  some  blood-sucking  Insect  (such  as  a  flea  or  bug)  was 
probably  the  place  where  the  above  described  extra-corporeal  phases  of 
the  parasite's  existence  would  be  found  to  occur.  This  has  been  recently 
proved  to  be  the  case  by  Patton  (93),  who  has  found  the  Flagellate  phases 
in  the  bed-bug  (Oimex  rotundatus  [macrocephalus]).  It  is  most  probable, 
therefore,  that  the  infection  of  human  beings  is  brought  about  by  this 
Insect,  which  serves  as  an  alternate  host. 

The  systematic  position  and  affinities  of  this  parasite  have  been  much 
discussed.  Leishman  at  first  considered  the  organisms  as  representing 
involution-forms  of  Trypanosomes,  being  largely  influenced  by  the  two 
chromatin  masses  ;  in  this  view  he  was  supported  by  Marchand  and 
Ledingham.  Later,  he  went  farther  and  suggested  that  they  perhaps 
represented  an  actual  stage  in  a  Trypanosome  life -cycle.  Laveran  and 
Mesnil,  taking  more  into  account  the  general  form  and  very  suggestive 
binary  fission,  thought  a  new  species  of  Piroplasma  was  concerned,  and 
named  the  bodies  Piroplasma  donovani ;  in  this  view  Donovan  and  others 
have  concurred.  Other  authorities  (e.g.  Christophers,  Ross,  and  Wright) 
thought  they  saw  in  the  parasite  an  entirely  different  kind  of  Sporozoan. 
Ross  called  the  splenic  type  Leishmania,  and  a  little  later,  Wright  termed 
the  ulcer- form  Helcosoma  tropicum.  Recently,  Rogers  has  placed  the 
Leishman-Donovan  form  in  the  genus  Herpetomonas,  on  account  of  the 
similarity  in  the  Flagellate- phase. 

It  is  probably  best  to  regard  the  parasites  as  generically  new  forms ; 
in  this  case  the  splenic  form  becomes  Leishmania  donovani  and  the  ulcer- 
type,  which  is  most  likely  a  separate  species,  L.  tropica.  The  organisms 
are  closely  related,  on  the  one  hand,  with  the  Herpetomouads,  and  on 
the  other  with  the  Piroplasmata.  With  regard  to  the  parasites  possessing, 
at  some  period  or  other,  a  trypaniform  structure,  the  complete  absence  of 
an  undulating-membrane  in  the  cultural  forms  is  no  proof  that  one  is  not 
present  under  certain  conditions  in  Nature.  For,  as  already  noted,  many 
Trypanosomes,  when  "  cultivated,"  may  have  a  very  slight  indication  of 
a  membrane  or  none  at  all.  Nevertheless,  it  is  by  no  means  improbable 
that  these  parasites  have  remained  solely  Herpetomonad  forms  and  have 
not  developed  the  characteristics  of  a  Trypanosome.  The  fact  that  the 
Flagellate-phase  is  only  known  to  occur  in  the  Invertebrate  host,  points 
very  strongly  to  this  being  the  original  primary  host.  In  this  connection 
the  Herpetomonas  lately  described  by  Patton  from  Culex  pipiens  (to  which 
reference  has  been  made  above)  is  very  interesting,  because  of  the  occur- 
rence of  resting- phases  resembling  the  Leishman  bodies.  Leishmania 
may  well  be  a  similar  form  which,  parasitic  in  a  sanguivorous  Insect, 
has  become  adapted  to  the  Vertebrate  host  in  its  resting,  gregariniform 
phase,  and  perhaps  never  develops  a  trypaniform  condition,  or  even  an 
active  flagellar  phase  therein.  Turning  to  the  other  side,  there  can  be 
little  doubt  that  the  Piroplasmata  are  intimately  connected  with  the 
Leishman-Donovan- Wright  bodies.  The  general  agreement  of  the  intra- 
cellular  forms  as  regards  appearance  and  binary  fission  has  been  noted 


above.  In  addition,  there  is  the  most  important  point  that  some  species 
of  Piroplasma  are  stated  to  show,  at  certain  times,  the  same  characteristic 
nuclear  dimorphism.  Schaudinn  was  the  first  to  notice  this,  in  the  case  of 
P.  canis ;  and  he  was  confirmed  by  Kossel  and  Weber.  Since  then  additional 
observations  to  the  same  effect  are  recorded  by  other  workers  (e.g.  Liihe) 
for  various  species.  This  being  so,  the  Piroplasmata  also  are  most 
probably  to  be  derived  from  Flagellate  forms.1 

(B)  A  word  or  two,  lastly,  with  reference  to  the  supposed  connection 
of  the  Spirochaetae  with  the  Trypanosornes.  Besides  the  instance  of 
Trypanosoma  (Spirochaeta)  ziemanni,  Schaudinn,  in  his  great  memoir  (I.e.), 
was  inclined  to  consider  that  other  Spirochaetae  (e.g.  S.  obermeieri  of 
relapsing  fever)  were  also  only  phases  in  the  lii'e-cycle  of  other  Haemo- 
flagellates.  Subsequently,  however,  as  a  consequence  of  his  investigations 
on  Spirochaeta  plicatilis,  the  type-species,  and  other  forms,  he  relinquished 
this  view,  finding  that  the  latter  were  of  a  totally  different  nature,  and 
should  rather  be  placed  with  the  Bacteria.  Much  has  since  been  written 
with  regard  to  the  nature  and  affinities  of  the  various  Spirochaetae.  We 
do  not  propose  to  go  into  the  general  question  here,  as  the  preponderance 
of  opinion  is  decidedly  against  these  organisms  belonging  to  the  Protozoa. 
It  is  only  necessary  to  mention  one  or  two  forms  which  have  been 
definitely  referred  to  the  Trypanosomes.  Certes,  in  1882,  described  a 
parasite  from  the  digestive  tube,  including  the  crystalline  style,  of  oysters, 
which  he  named  Trypanosoma  balbianii.  A  few  years  ago  Laveran  and 
Mesnil  (99)  re-examined  this  organism,  and  came  to  the  conclusion  that 
it  was  not  a  Trypanosome  but  a  Bacterium,  allied  to  Spirochaeta.  Other 
workers  who  have  recently  observed  this  form  also  agree  that  its  structure 
shows  none  of  the  essential  features  of  a  Trypanosome,  but,  on  the  contrary^ 
greatly  resembles  that  of  a  true  Spirochaete.  Perrin,  it  may  be  noted, 
has  endeavoured  (100)  to  connect  it  with  Schaudinn's  bipolar  "  Ur- 
haemoflagellate."  This  idea  has  received  no  support,  and  indeed  Perrin's 
whole  paper  is  most  unconvincing.  Another,  much  more  important 
example  is  that  of  the  remarkable  spirochaetiform  parasite  first  described 
by  Schaudinn  and  Hoffmann  (103)  in  cases  of  syphilis,  and  which  is 
now  considered  to  be  most  likely  the  cause  of  that  disease.  Schaudinn 
found  (102)  that  this  organism  differs  in  many  ways  from  an  ordinary 
Spirochaeta,  and  placed  it  in  a  new  genus  Treponema  as  T.  pallidum. 
In  a  recent  memoir  (101),  Krzysztalowicz  and  Siedlecki  have  given  a 
detailed  account  of  this  organism,  and  state  that  they  have  observed 
distinct  trypaniform  stages  in  its  life-cycle.  For  this  reason  they  con- 
sider it  to  be  allied  to  the  Trypanosomes  and  place  it  actually  in  the 
genus  Trypanosoma,  as  T.  luia.  This  view  lacks,  as  yet,  corroboration, 
and  so  here,  as  in  the  case  of  Schaudinn's  research,  the  question  must 

1  Since  this  was  written  we  are  able  to  add  that  confirmation  of  this  view  is  forth- 
coming. In  a  most  important  note,  Miyajima  (Philipp.  J.  Sci.  ser.  B,  ii.  1907,  p. 
83)  describes  the  development  of  Flagellate-phases  in  cultures  of  a  Piroplasma 
(cf.  parvum)  of  cattle  in  Japan.  In  seventy-two  hours,  forms  with  well-developed 
undulating-membrane  were  numerous.  The  author  seems  to  have  carefully  guarded 
against  the  possibility  of  this  highly-interesting  occurrence  being  due  to  undetected 
Trypanosomes  present  in  the  blood. 


be  left  unsettled.  There  is  one  point,  however,  which  may  not  be 
without  significance,  namely,  the  considerable  resemblance  between  the 
biology  of  this  parasite  in  relation  to  its  host  (i.e.  as  regards  mode  of 
infection,  habitat,  connection  with  the  lesions,  etc.)  and  that  of  Trypano- 
soma  equiperdum,  the  cause  of  Dourine  or  "  horse-syphilis "  (cf.  above, 
pp.  197,  206). 


As  this  article  goes  to  press,  a  most  interesting  note  by  Roubaud 
(G.B.  Ac.  Sci.,  24th  Feb.  1908,  p.  423)  comes  to  hand.  This  worker 
has  been  investigating  the  relation  between  certain  lethal  Trypanosomes 
(T.  fjambiense,  T.  brucii,  T.  dimorphon,  and  others)  and  Glossina  palpalis, 
and  finds  that  the  parasites  undergo  important  changes  as  soon  as  they 
arrive  in  the  proboscis  of  the  Tsetse-fly.  The  kinetonucleus  passes  to  the 
middle  of  the  body,  the  undulating-membrane  disappears,  the  flagellum 
becomes  short  and  thickened,  and  the  parasites  quickly  attach  themselves 
to  the  wall  of  the  proboscis  by  the  flagellar  end.  The  whole  process  may 
be  accomplished,  indeed,  in  five  minutes.  Moreover,  active  multiplica- 
tion goes  on,  and  after  a  time  an  immense  number  of  attached  Trypano- 
somes are  present  throughout  the  entire  proboscis,  often  grouped  in 
masses  or  colonies.  This  "  temporary  culture "  (culture  d'attente) 
persists  for  two  days  in  the  case  of  T.  brucii,  and  longer — up  to  five  to  six 
days — in  the  other  forms. 

This  remarkable  development  is  apparently  specific  for  Glossinae  ; 
it  only  occurs  in  a  small  number,  and  is  doubtless  due  to  the  influence  of 
special  properties  of  the  salivary  fluid.  As  Roubaud  remarks,  it  prob- 
ably affords  an  explanation  of  the  selective  role  played  by  the  Tsetses  in 
the  propagation  of  different  trypanosomoses  in  Africa.  Roubaud,  how- 
ever, considers  that  these  forms  found  in  the  proboscis  are  the  only  ones 
capable  of  giving  rise  to  an  infection  in  a  Vertebrate  after  the  lapse  of 
twenty-four  hours.  This  is  going  too  far,  in  view  of  the  facts  now  known 
with  regard  to  the  length  of  time  Trypanosomes  may  live  and  develop 
in  the  digestive  tract  of  Glossinae  (cf.  pp.  200,  230).  It  is  noteworthy  that 
Roubaud  was  unable  to  obtain  a  successful  inoculation  from  a  proboscis 
so  infected.  Moreover,  the  repeated  failures  of  investigators  to  infect 
animals  from  flies  after  forty-eight  hours  (cf.  pp.  199,  200)  seem  to  show 
that  the  later-developed  "  proboscis-forms  "  at  all  events  are  not  infective, 
since  they  may  reasonably  be  supposed  to  have  been  present  in  some  of 
the  many  experiments  tried.  On  the  other  hand,  there  is  an  important 
observation  made  by  Bruce  when  working  on  T.  brucii,  to  which  Mincliin 
(58,  p.  210)  has  drawn  attention,  showing  that  "wild"  flies,  caught 
while  feeding  on  a  healthy  animal,  could  infect  another  animal  on  which 
they  were  subsequently  fed.  This  certainly  points  to  the  presence  of 
some  developmental  phases  in  the  Insect  other  than  Roubaud's  proboscis- 
forms  ;  the  proboscis  had  been  presumably  "cleaned"  by  the  first  bite — 
on  the  uninfected  animal  on  which  the  fly  was  caught.  And  this  view  is 
entirely  borne  out  by  Stuhlmann's  recent  research,  summarised  in  the  body 
of  this  article. 




[In  the  compilation  of  this  list,  Nabarro's  edition  of  Laveran  and  Mesnil's 
Treatise  has  been  of  considerable  service  to  the  writer.  ] 


?  Bovidae  (Indian,  indigenous)     . 
?  B.  (various,  African) 


Catoblepas  gnu,  gnu,  "wildebeeste 
?  Cattle  ("hill,"  India) 

Cavia  cobaya,  guinea-pig 

Cricetus    frumenlarius    (arvalis), 


Hydrochoerus  capybara,  capybara 
Lepus  cuniculus,  rabbit 
Meles  taxus,  badger     . 
Miniopterus  schreibersii,  bat 
Mus  decumanus,  se\ver-rat  . 

M.  rattus,  black  rat,  M.  rufescens 
M.  sylvaticus,  field  rat 
M.  musculus,  mouse    . 

M.  niveiventer,  rat  (Indian) 
Myotis  murinv-s,  a  bat 

Myoxus  avellanarius,  M.  glis,  dormice 

Nesokia  (Mus)  gigantcus,  bandicoot 
Phyllostoma  sp.     See  under  Stegomyia 
Pipistrellus  pipistrellus,  bat 

Pteropus  medius,  a  bat 

Sciurus  palmarum,  squirrel  (Indian)  . 
Spermophilus    guttatus,    S.     musivtis, 


Strepsiceros  capensis,  "koodoo" 
Talpa  europaea,  mole 
Tragelaphus  scriptus  sylvaticus,  ' '  bush  - 

buck  " 

Trypanosoma  evansi  (Steel). 

T.  theileri,  Lav.,  and  T.  transvaaliense, 

Lav.  [most  probably  =  T.  theileri]. 
T.  brucii,  Bradford  and  Plimmer. 
T.  brucii. 
T.   himalayanum,    Lingard    (syn.    T. 

lingardi,    Blanchard)    [perhaps    = 

T.  theileri]. 
A  Trypanosome  [possibly  a  Trypano- 

plasma],  Kunstler,  1883. 
T.   rabinowitschi,   Brumpt  (syn.    Try- 

panozoon  criceti,  Liihe). 
T.  equinum,  Voges. 
T.  cuniculi,  Blanchard. 
T.  pestanai,  Bettencourt  and  Franga. 
A  Trypanosome  [Dionisi,  1899]. 
T.    lewisi   (Kent)  ;    T.    longocaudense, 

Lingard  [probably  =  T.  lewisi}. 
T.  lewisi  (Kent). 
T.  sp.  [lewisi  1],  Gros,  1845. 
T.  duttoni,  Thiroux  ;   T.  musculi  [syn. 

T.  d.  ?],  Kendall. 
T.    longocaudense,    Lingard   [probably 

=  T.  lewisi]. 
T.    nicolleorum,    Sergent,    E.   and  E. 

[perhaps    syn.     T.     vespertilionis, 

T.  blanchardi,  Brumpt  (syn.  T.  myoxi, 

T.  bandicotti,  Lingard. 

T.  sp.  (compared  with  T.  nicolleorum), 

A  Trypanosome  [Donovan,  in  Lav.  and 

Mesn.,  1904]. 

T.  (Trypanozoon)  indicum,  Liihe. 
A  Trypanosome  [Chalachnikov,  1888]. 

T.  brucii,  Br.  and  PI. 
T.  talpae,  Nabarro. 
T.  brucii. 



Vespertilio  kuhli,  bat . 

V.  noctula,  bat  ..... 
Vesperugo    nattereri,     V.    pipistrellus 
("pipistrelle"),  V.  serotinus,  bats 

T.   nicolleorum,  Sergeut,  E.  and  E.  ; 

T.  vespertilionis,  Serg.  [both  perhaps 

synn.  T.  vespertilionis,  Battaglia], 
T.  vespertilionis,  Battaglia. 
T.  dionisii,    Bettencourt  and  Fran9a 

[perhaps    syn.     T.     vespertilionis, 


Various  Trypanosomes  which  have  been  given  distinct  names  have  been  lately  described 
from  certain  Equiclae  and  Bovidae  in  different  regions  of  Africa,  as  the  cause  of  more  or  less 
pronounced  trypanosomosis.  It  is  probable  that  some  of  these,  at  any  rate,  are  really  forms 
of  other  better-known  African  parasites.  They  are  mentioned  here,  in  order  to  complete  an 
enumeration  of  species,  for  purposes  of  reference.  They  are  T.  cazalboui,  Lav.  ;  T.  congdense, 
Broden  ;  T.  nanurn,  Lav.  (an  extremely  small  form);  T.  pecaudi,  Lav.  ;  T.  soudanense,  Lav.  ; 
7'.  mi  ix,  Ochmann  ;  and  T.  vivax,  Ziemann.  The  true  (natural)  hosts  are  uncertain. 


Agelaius  phoeniceus,  red-winged  black- 

Alcyon  sp.,  kingfisher  (Cameroon) 

Asturinula  monogrammica,  hawk 
(Congo  State) 

Athene  noctua,  little  owl 

A.  brama,  owl  (Madras) 

Buteo  lineatus,  red-shouldered  hawk    . 
Bycanistes  buccinator,  trumpeter  hnrn- 


Chelidon  urbica,  house-martin 
Colaptus  auratus, "  flicker  " 
Columba  sp.,  pigeon  (Indian) 
Coracias  garrulu,  roller-bird 
Corvus  sp.,  crow  or  raven  (Indian) 


Crithagra  sp.,  "millet-eater" 
Cyanocitta  cristata,  blue  jay 

Dryobates  villosus,  hairy  woodpecker   . 

Emberiza  citrinella,  yellow-hammer     . 
Estrelda  estrelda,  "millet-eater" 
Fringilla  (Carduelis)  carduelis,  gold- 
F,  coelebs,  chaffinch     . 


T.  atrium  (type  L.  and  M.),  [Novy  and 

M'Neal,  1905]. 

A  Trypanosome  [Ziemann,  1905]. 
A  Trypanosome   [Button,    Todd   and 

Tobey,  1907]. 
Trypanomorpha    ( Trypanosoma)    noc- 

tuae  (Schaud.)  ;  also  Trypa/nosoma 

[Spirocliacta  ?]  ziemanni  (Lav.). 
A  Trypanosome  [Donovan,  in  Lav.  and 

Mesn.,  1904]. 

T.  mesnili,  Novy  and  M'Neal. 
A   Trypanosome    [Button,    Todd   and 

Tobey,  1906]. 

A  Trypanosome  [Petrie,  1905]. 
T.  aviurn  (type  Lav.  and  Mesn.). 
T.  hannae,  Pittaluga. 
T.  "avium,"  Banilewsky. 
A  Trypanosome  [Hanna,  1903]. 
A  Trypanosome  ?  [Gros,  1845]. 
T.  sp.  [Button  and  Todd,  1903]. 
T.  avium  (type  L.  and  M.) ;  also  T. 

sp.  [Novy  and  M'Neal,  1905]. 
T.    sp.    incert.    [Novy    and    M'Neal, 

T.    sp.,    perhaps    avium    [Cerqueira, 


A  Trypanosome  [Petrie,  1905]. 
T.  johnstoni,  Button  and  Todd. 
T.  sp.  [Sergent,  E.  and  E. ,  1904]. 

A  Trypanosome  [Ziemann,  1898  ;  also 

Petrie,  1905]. 
A  Trypanosome  ?  [Gros,  1845]. 



ffarporhynchus  rufus,  brown  thrasher 
Hirundo  rustica,  swallow     . 

Icterus  galbula,  Baltimore  oriole . 
Laniarius  cruentus,  shrike  (African)    . 
Linota  (Acanthis)  rufescens,  redpoll 
Melospiza  fasciata,  song-sparrow  . 
Merula  migratoria,  robin  (American)  . 
M.  merula,  blackbird  .... 
Milvus  govinda,  kite  (Indian) 

Neophron percnopterus,  vulture  (African ) 
Nicticorax  gardenia  (Brazil) 

Padda  oryzivora,  Java  sparrow  . 
Passer  domesticus,  sparrow  .  -  . 
Passerine  birds,  many  (except  Corvus 

and  Pica) 
Polyplectrum        germani,        pheasant 


Scolephagus  carolinus,  rusty  blackbird 
Sialia  sialis,  bluebird 
Spinus  tristis,  goldfinch  (American) 
Sylvia  atricapilla,  black-cap  warbler    . 
Syrnium  aluco,  tawny  owl  . 

2'achyphormus  ornata .... 
Treron  calva,  dove  (Angola) 
Turdus  musicus,  song-thrush 
Troglodytes  aedon,  house-wren 
Zenaidura  macroura,  mourning-dove    . 

A  Trypanosome  [Novy  and  M'Neal, 

T.  mathisi,  Serg.,  E.  and  E.  ;  a  Try- 
panosome (T.  m.  ?)  fPetrie,  1905]. 

T.  avium  (type  L.  and  M. ). 

A  Trypanosome  [Neave,  1906]. 

T.  sp.  [original  observation]. 

T.  avium  (type  L.  and  M.). 

T.  avium  (type  L.  and  M.). 

A  Trypanosome  [Petrie,  1905]. 

A  Trypanosome  [Donovan,  in  Thiroux, 

A  Trypanosome  [Neave,  1906]. 

T.  sp.,  perhaps  avium  [Aragao,  in  Cer- 
queira,  1906]. 

T.  paddac,  Thiroux. 

T.  avium  (type  L.  and  M.). 

Trypanosomes  [Sjb'bring,  in  N.  and 
M'Neal,  1905]. 

T.  polyplectri,  Vassal. 

T.  sp.,  Novy  and  M'Neal. 
T.  avium  (type  L.  and  M. ). 
T.  laverani,  Novy  and  M'Neal. 
T.  sp.  [Sergent,  E.  and  E.,  1904]. 
T.  avium,  Danil.,   emend.  Lav.  ;  also 
"T."  [Leucocytozoon]  ziemanni  (Lav.). 
A  Trypanosome  [Cerqueira,  1906]. 
A  Trypanosome  [Wellmau,  1905]. 
A  Trypanosome  [Petrie,  1905]. 
A  Trypanosome  [N.  and  M'N.,  1905]. 
T.  avium  (type  L.  and  M.). 


Crocodile  (Uganda;      .... 
Crocodilus  cataphractus  ?  (Congo) 

Damonia  reevesii,  tortoise   . 


Mabuia    raddonii,    a    lizard    (French 

Python        .         .         . 

Snake  (unspec.,  Gambia) 

Tortoise    (Indian — Emys  or    Kachuga 

Tortoise  (unspec.,  Gambia) 

A   Trypanosome   [Minchin,   Gray  and 

Tulloch,  1906]. 
A  Trypanosome  [Dutt.,  Todd  and  Tob., 


T.  damoniae,  Lav.  and  Mesn. 
A  Trypanosome  [Gehrke,  1903]. 
T.  boueti,  Martin. 

"  T."  pythonis,    Robertson    [really    a 

A    Trypanosome   [Dutton   and   Todd, 

A  Trypauosome  [Simond,  in  L.  and  M., 

A   Trypanosome   [Dutton    and   Todd, 





Bufo  vulgaris  and  viridis,  toads  . 
B.  rcticulatus  (Somaliland) . 
Diemyctulus      viridescens      (American 

Frogs  (unspec.,  Gambia) 

Hyla  arborca  and  H.  viridis,  tree-frogs 

//.  latcristriga  (?),  Brazil 
Rana  angolcnsis  (Transvaal) 
H.  esculcnta,  edible  frog 

7i.  temporaria 

7v'.  t.  (?)  (Hong  Kong)  . 
.K.  theileri  (Transvaal) 
It.  trinodis  (?)  and  other  sp.  (Gambia) 

T.  rotatorium  (Mayer). 
T.  somalcnse,  Brumpt. 
A  Trypanosome  [Tobey,  1906]. 

T.  mega  and  T.  karyozeukton,  Duttoii 
and  Todd. 

T.  rotatorium  (Mayer);  T.  sp.  [?], 
Lav.  and  Mesn. 

T.  borreli,  Marchoux  and  Salimbeni. 

T.  nelspruitense,  Lav. 

T.  rotatorium  (Mayer).  (Syn.  T. 
loricatum  or  costatum  (Mayer)  and 
T.  rotatorium  (Mayer),  Fran9a  and 
Athias  ;  T.  r.  var.  nana,  Sergent,  E. 
and  E. ;  T.  inopinalum,  Sergent, 
E.  and  E.  ;  T.  elegans  and  T.  undu- 
lans,  F.  and  A.  [doubtful  species].) 

T.  rotatorium  (Mayer). 

T.  belli,  Nabarro. 

T.  nelspruitense,  Lav. 

T.  rotatorium  (Mayer). 

(Tpl.  —   Trypanoplasma.) 

Abramis  brama,  bream 

Acerina  cernua,  pope  .... 

A  nguilla  vulgar  is,  eel          ... 
Bageus  bayard,  bagara  (Nile) 
Barbus  camaticus  (India)    . 

B.  fluviatilis,  barbel   .... 

Blennius  pholis,  blenny 

Bothus  rhombus  (Rhombus  laevis),  brill 

Box  boops    ...... 

Callionymus  dracunculus    . 
Carassius  auratus,  goldfish 

C.  vulgaris,  Prussian  carp  . 

Clarias    (Silurus)    clarias,    a    Silurid 

C.  angolensis  (Congo  State) 

Cobitis  barbatula,  loach 

T.    abramis,    Lav.    and   Mesn.  ;    Tpl. 

abramidis,  Brumpt. 
T.  accrinae,  Brumpt ;  &  Trypanoplasm 

[Keysselitz,  1906]. 
T.  granulosum,  Lav.  and  Mesn. 
A  Trypanosome  [Neave,  1906]. 
A  Trypanosome  [Lingard,  1904]. 
T.      barbi,      Brumpt ;      Tpl.      barbi, 


T.  delagei,  Brumpt  and  Lebailly. 
T.  bothi,  Lebailly. 
Tpl.  [?]  intestinalis,  Leger. 
T.  callionymi,  Brumpt  and  Lebailly. 
T.  danilewskiji,  Lav.  and  Mesn. 
T.  carassii  (Mitropban.).  (Syn.  Haema- 

tomonas  c.,  Mitis ;  T.  piscium  and  T. 
fusiforme  piscium,  Danilewsky. ) 
T.  clariac,  Montel. 

A   Trypauosome   [Button,    Todd    and 

Tobey,  1906]. 
T.    barbatulae,    L^ger ;    Tpl.    varium, 




C.  fossilis    . 

Coitus  bubalis 

C.  gobio,  river  bull-head 

Cycloptcrus  lumpus,  lump-fish 
Cyprinus  carpio,  carp .... 

Esox  lucius,  pike         .... 

Gobio  fluviatilis,  gudgeon    . 
G.  giuris  (India)          .... 
Gobius  niger,  goby       .... 
Leuciscus      (Scardinius),      erythroph- 

thalmus,  rudd  or  red-eye 
L.  idus,  L.  cephalus,  L.  rutilus,  roaches 

L.  spp 

Limanda  platessoides  .... 
Lota  vulgaris      ..... 

Macrodon  malabaricus  (Brazil)    . 
Macrones  seenghala,  M.tengara,Si\nri(.\s 

M.  cavasius  (India)     .... 

Mugil  sp.,  noke  (Nile) 

OphiocepJialus  striatus,  Silurid  (India) 

Perca  fluviatilis,  perch 

Phoxinus  lacvis,  minnow 

Platoplirys  laternae      . 

Pleuronectcs  flesus    (Flesus   vulgaris), 

P.  platessa  (Platessa  vulgaris),  plaice   . 

Polypterus  sp.,  dabib  (Nile) 

Raia  clavata,   E.    macrorhynchus,    B. 

mosaica,  and  E.  punctata,  rays 
E.  microccllata    ..... 
Ehamdia  queler  (Brazil) 
Saccobratichus  fossilis,  a  Silurid   . 
Salmo  fario,  trout       . 

Scyllium  canicula,  S.  stellare,  dogfish 

T.  cobitis  (Mitroph. ).     (Syn.  Haemato- 

monas  c.,  Mitr.  ;    T.  piscium  and 

T.  fusiformc,  Daiiilewsky. ) 
T.  cotti,  Brumpt  and  Lebailly. 
T.  langeroni,  Brumpt ;  Tpl.  guernei, 


Tpl.  [?]  ventricuU,  Keysselitz. 
T.  danilewskiji,  Lav.  and  Mesn. ;  Tpl. 

cyprini,  Plehn. 
T.  remaki,  Lav.  and  Mesn.  ;  Tpl.  sp. 

[Minchin,  1908]. 
T.  elegans,  Brumpt. 
T.  sp.  [Castellani  and  Willey,  1905]. 
T.  gobii,  Brumpt  and  Lebailly. 
Tpl.    Worrell,    Lav.    and    Mesn. ;    T. 

scardinii,  Brumpt. 
A     Trypanosome    and    Trypanoplasm 

[Keysselitz,  1906].     [Probably  Tpl. 

borreli  and  T.  leucisci.] 
T.  leucisci,  Brumpt. 
T.  limandae,  Brumpt  and  Lebailly. 
A    Trypanosome    and    Trypanoplasm 

[Keysselitz,  1906].  . 
T.  macrodonis,  Botello. 
A  Trypanosome  [Lingard,  1899]. 

A      Trypanosome      [Castellaui      and 

Willey,  1905]. 

A  Trypanosome  [Neave,  1906]. 
A  Trypanosome  [Lingard,  1899]. 
T.  percae,  Bmmpt  ;   also  a  Trypauo- 

plasm  [Keysselitz,  1906]. 
T.  danilewskyi  (?),  Lav.  and  Mesn.;  T. 

phoxini,  Brumpt ;  Tpl.  borreli,  Lav. 

and  Mesn. 

T.  laternae,  Lebailly. 
T.    flesi,    Lebailly    (syn.    T.    pleuro- 

nectidium,  Robertson). 
T.  platessae,  Lebailly  (syn.  T.  pleuro- 

nectidium,  Roberston). 
A  Trypanosome  [Neave,  1906]. 
T.  raiae,  Lav.  and  Mesn. 

A  Trypanosome  [Robertson,  1906]. 

T.  rhamdiae,  Botello. 

T.  saccobranchi,  Castellani  and  Willey. 

Tpl.  truttae,  Brumpt.  [Valentin,  in 
1841,  observed  a  Haematozoan, 
which  was  probably  either  a 
Trypanosome  or  a  Trypanoplasm.] 

T.  scyllii,  Lav.  and  Mesn. 



tiilurus  giants     .... 
Solea  vulgaris,  sole 
Squalius  (Leuciscus)  cephalits,  chub 
Synodontis  schal,  gargur  (Xile)    . 
T!i»''i  tinea,  tench 

Trichognster  fasciatus  (India) 

A  Trypanosome  [Keysselitz,  1906]. 

T.  soleae,  Lav.  and  Mesu. 

T.  squalii,  Brumpt. 

A  Trypanosome  [Neave,  1906]. 

T.  tincae,  Lav.  and  Mesn.  ;  a  Trypano- 

plasm  [Keysselitz,  1906], 
A  Trypanosome  [Lingard,  1899]. 


Anopheles  maculipennis 

A.  m.  (larvae)      .... 

Anopheles  sip.,  mosquitoes  (India) 

Bombyx  mori,  silkworm 
Chironomus  plumosus 
Cimex  rotundatus,  bed-hug  (India) 
Culexfatigans     .... 

C.  pipiens  ..... 

Dasyphora  pratorum   . 
Glossina  fusca     .... 
G.  morsitans  and  G.  pallidipes     . 
G.  jtalpalis          .... 

G.  tachinoides      .... 
Haematopinus  spinulosus,  rat-louse 
Haematopota  italica 
Hippobosca  rufipes,  (?)  //.  maculata 
Homalomyia  scalaris  . 
Mclophagus  ovinus,  sheep-louse   . 

Musca  domestica  ..... 
Nepa  cinerea  ..... 
Pollenia  rudis  ..... 
Pulex  sp.,  fleas  ..... 

Sarcophaga  haemorrhoidalis,  blow-fly 
Stcgomyia  fasciata       .... 
S.  f.  (an  individual  which  had  fed  on 

a  bat,  Phyllostoma) 
Stomoxys  calcitrans      .... 

Tabanus  rjlaucopsis      .... 

Crithidia  fasciculata,  L^ger. 

A  Herpetomonad  (cf.  with  H.  jaculum) 
[Sergent,  E.  and  E.,  1906]. 

Herpetomonads  (said  to  resemble 
Leger's  Crithidia)  [Ross,  1898  ; 
Christophers,  1901,  and  others]. 

Herpetomonas  bombycis,  Levaditi. 

Crithidia  campanulata,  Leger. 

Leishmania  (Piroplasma)  donovani. 

Herpetomonads  [Ross,  1898  ;  Chris- 
tophers, 1901  ;  Patton,  1907]. 

Trypanomorpha  nociuae  (Schaud.)  ; 
Crithidia  fasciculata  ;  "  Trypano- 
soma"  (Herpetomonas)  culicis,  N., 
M'N.,  and  Torrey  ;  H.  algeriense, 
Sergent,  E.  and  E.  ;  H.  sp.,  indet. 
[Patton,  1907]. 

H.  lesnei,  Leger. 

T.  brucii  ;  perhaps  T.  gambiense. 

(?)  T.  brucii. 

T.  grayi,  Novy  ;  T.  tidlochii,  Minchin  ; 
(?)  T.  dimorphon,  Dutt.  and  Todd. 

(?)  T.  brucii ;  (?)  T.  gambiense. 

(?)  T.  lewisi. 

(?)  //.  subulata,  Leger. 

T.  thcileri  (probably). 

//.  (cf.  muscae-domesticae)  [Leger]. 

"  Trypanosome-like  parasites  "  [Pfeiffer, 

If.  muscae-domesticae,  Burnett. 

//.  jaculum,  Leger. 

//.  (cf.  m.-d.)  [Leger]. 

T.  lewisi  (probably) ;  a  Herpetomonad 
[Dalfour,  1906]. 

H.  sarcophagae,  Prowazck. 

//.  algeriense,  Sergent,  E.  and  E. 

A  "Trypanosome"  [Durham,  1900]. 

(?)  T.     equinum  ; 
[Gray,  1906]. 
//.  subulata,  Leger. 

a     Herpetomonad 


T.  lineola  and  other  sp.       .         .         .       (?)  T.  evaiisi. 

T.  tergestimis      .....       Herpetomonas      (Crithidia)      minuta, 


Tanypus  sp H.  gracilis,  Ldger. 

Theicomyxa fusca        ..        .         .         .       H.  (cf.  m.-d.}  [Leger]. 
"Water-bug"  (India)  ...       A  Herpetomonad  [Patton,  1907]. 


Ehipicephalus     sanguineus,     dog-tick       "  T."   christophcrsi,    N..    M'N. ,    and 
(India)  Torrey. 


Calobdella punctata      .',»-    .         .         .       T.  cotti  and  T.  soleae  [Brunipt]. 

Helobdella  algira         .         .         .         .       T.  inopinatum  [Billet]. 

Hemiclepsis  marginata         .         .         .       Tpl.  varium  [Le'ger]. 

H.  sp.          ......        T.    abramis,     acerinac,     barbi,    dani- 


remaki,   squalii;    perhaps   also    T. 

barbatulae   (?),    langeroni,   Icucisci, 

scardinii  [Brumpt].    Tpl.  abramidis 

Piscicola  sp.         .....       T.    barbatulae  [Leger]  ;    Tpl.   borreli, 

barbi,  guernci,  (tytruttae  [Brumpt]. 
P.  geometra Tpl.  borreli ;  also  other  Trypanoplasms 


Pontobdella  muricata  T.  raiae  [Robertson]. 

P.  sp.  ......        T.  scyllii  [Brumpt]. 


Abyla  pentagona,    Cucubalus    kochii,       Trypanophis  grobbeni  (Poohe). 
Halistemma  tergestinum,  and  Mono- 
phycs  gracilis 


I.  Relating  to  the  Trypanosomes. 
A.  Comprehensive  works. 

1.  Laveran,  A., and. Mesnil,  F.  Trypanosomes et  try panosomiases.   Paris  (Masson 

et  Cie.),  1904.  An  English  edition,  translated  and  considerably  enlarged 
and  brought  up  to  date  by  D.  Nabarro,  has  lately  been  published  (Londou, 
Bailliere,  Tindall  and  Cox,  1907,  581  pp.,  81  text-figg.). 

2.  Liihe,  M.     Die  im  Blute  schmarotzenden  Protozoen.    In  Mense's  Handbuch 

der  Tropenkrankheiten,  vol.  iii.  pt.  i.  (Leipzig,  J.  A.  Barth,  1906),  pp.  69- 
268,  3  pis.,  text-figg. 

3.  Woodcock,  H.  M.     The   Haemoflagellates.      Q.J.   Micr.   Sci.   1.,   1906,  pp. 

151-331,  65  text-figg. 


B.  List  of  the  more   important   memoirs    cited   in    the   text.      (N.B.   Full 
references  to  the  existing  literature  are  given  in  each  of  the  above  works.) 

4.  Billet,  A.     Culture  d'un  Trypanosome  de  la  grenouille  chez  tine  Hirudinee  : 

relation  atitogenique  possible  de  ce  Trypanosome  avec  tine  Hemogregarine. 
O.K.  Ac.  Sci.  cxxxix.  p.  574,  1904. 

5.   Sur  le  Trypanosoma  inopinatvm  .  .  .  et  sa  relation  possible  avec  les 

Drepanidium.    C.R.  Soc.  Biol.  Ivii.  p.  161,  16  figg.,  1904. 

6.  Bradford,  J.  II. ,  and  Plimmer,  H.  G.    The  Trypanosoma  brucii,  the  Organism 

found  in  Nagana  or  the  Tsetse-fly  Disease.     Q.J.  Micr.  Sci.  xlv.  p.  449, 
2  pis.,  1902. 

7.  Bruce,  D.    Reports  on  the  Tsetse-fly  Disease  or  Nagana.    Ubombo,  Zululand, 

1895  and  1896-;  London,  1897  and  1903. 
8. ,  Nabarro,  D.,  and  Greig,  E.  D.  [Reports  on  Sleeping-Sickness  and  various 

Animal  Trypanosomoses  in  Uganda.]     Roy.  Soc.  Comm.,  1903-1907. 
9.  Bruin/it,  E.     Contribution  a  1'etude  de  1'evolution  das  Hemogregarines  et  des 

Trypauosomes.     C.R.  Soc,  Biol.  Ivii.  p.  165,  1904. 

10.   Sur  quelques  especes  nouvelles  de  Trypauosomes  parasites  des  poissons 

d'eau  douce  ;  leur  mode  devolution.     Op.  cit.  Ix.  p.  160,  1906. 

11.  Mode  de  transmission  et  evolution  des  Trypanosomes  des  poissons ; 

description  de  quelques  especes  de  Trypanoplasmes  des  poissons  d'eau  douce ; 
Trypanosome  d'un  crapaud  africain.     T.c.  p.  162,  1906. 

12.  Experiences  relatives  au  mode  de  transmission  des  Trypanosomes  et 

des  Trypauoplasmes  par  les  Hirudinees.     Op.  cit.  Ixi.  p.  77,  1906. 

13.  Role  pathogeue  et  mode  de  transmission  du  Trypanosoma  inopinatum, 

Ed.  et  Et.  Sergent.     Mode  d'inoculatiou  d'autres  Trypanosomes.      T.c. 
p.  167,  1906. 

14.  -      -     De  1'heredite  des  infections  a  Trypanosomes  et  Trypanoplasmes  chez 

les  hotes  intermediares.     Op.  cit.  Ixiii.  p.  176,  1907. 

15.  and   Lebailly,    C.      Description    de    quelques    nouvelles    especes   de 

Trypanosomes    et    d'Hemogregarines   parasites    des   Teleosteens   marins. 
C.R.  Ac.  Sci.  cxxxix.  p.  613,  1904. 

16.  Buffard,  M.,  and  Schneider,   G.     Le  Trypanosome  de  la  Dourine.     Arch. 

Parasitol.  iii.  p.  124,  pis.,  1900. 

17.  Castellani,  A.     Trypanosoma  and  Sleeping-Sickness.     Reports  S.S.  Comm. 

Roy.  Soc.  i.  and  ii.,  1903. 

18.  Danilewsky,  .     Recherches  sur  la   parasitologie  comparee  du  sang  des 

oiseaux.     Kharkotf,  1888-1889. 
19. Zur  Parasitologie  des  Blutes.     Biol.  Centrlbl.  v.  p.  529  (1885). 

20.  Dutton,  E.     Note  on  a  Trypanosoma  occurring  in  the  Blood  of  Man.     Brit. 

Med.  Jouru.,  1902,  ii.  p.  881,  1  fig. 

21.  and   Todd,  J.  L.     First  Report  of  the  Trypanosomosis  Expedition  to 

Senegambia  (1902).     Mem.  Livpl.  Sch.  Trop.  Med.  No.  11,  1903. 

22.  Franca,  C.,  and  Athias,  C.   Recherches  sur  les  Trypanosomes  des  Amphibiens  : 

I.    Les  Trypanosomes   de   la  Eana  esculenta.      Arch.    Inst.    R.    Bact., 
Lisbonne,  i.,  1906. 

23.  Gray,  A.  C.,  and  Tulloch,  F.  M.     The  Multiplication  of  the  Trypanosoma 

gambiense  in  the  Alimentary  Canal  of  Glossina palpalis.     Rep.  S.S.  Comm. 
Roy.  Soc.  No.  6,  p.  282,  1  pi.,  1905. 

24.  Gruby.     Recherches  et  observations  sur  une  nouvelle  espece  d'Hematozoaira 

(Trypanosoma  sanguinis).     C.R.  Ac.  Sci.  xvii.  p.  1134,  1843;  and  Ann. 
Sci.  Nat.  (3),  i.  p.  105,  7  figg.,  1844. 


25.  Hanna,  W.     Trypanosoma  in  Birds  in  India.     Q.J.  Micr.  Sci.  xlvii.  p.  433, 

1  pi.,  1903. 

26.  Keyssclitz,  G.     Ueber  Trypanophis  grobbcni  (Trypanosoma  g.,  Poche).     Arch. 

Protistenk.  iii.  p.  367,  3  figg.,  1904. 

27. Generations-  und  Wirthswechsel  von  Trypanoplasma  borreli,  Lav.  et 

Mesn.     Arch.  Protistenk.  vii.  p.  1,  text-figg.,  1906. 

28.  Koch,  A'.     Vorlaufige  Mittheilungen  iiber  die  Ergebnisse  meiner  Forschungs- 

reise    nach    Ostafrika.      Deutsch.    med.    Wocheuschr.,    1905,    p.    1865, 

29.  Ueber  den  bisherigen  Verlauf  der  deutschen  Expedition  zur  Erforsch- 

ung  der  Schlafkrankheit  in  Ostafrika.     Op.  cit.  1906,  Appendix,  p.  51 ; 
also  1907,  p.  49.     Schluss-Bericht.     Op.  cit.  1907,  p.  1889. 

30.  Lankester,  E.  R.     On  Undulina,  the  type  of  a  New  Group  of  Infusoria.     Q.J. 

Micr.  Sci.  xi.  p.  387,  4  figg.,  1871. 

31.  -     -    The  Sleeping-Sickness.     Quart.  Rev.,  July  1904,  p.  113,  7  figg. 

32.  Laveran,  A.     Sur  un  nouveau  Trypanosome  des  Bovides.     C.R.  Ac.   Sci. 

cxxxiv.  p.  512,  1902. 

33.  Au  sujet  de  deux  Trypanosomes  des  Bovides  du  Transvaal.     Op.  cit. 

cxxxv.  p.  717,  5  figg.,  1902. 

34.  Sur  un  Trypanosome  d'une  chouette.     C.R.   Soc.  Biol.  Iv.   p.   528, 

2  figg.,  1903. 

35.  Contribution  a    1'etude    de   Hacmamoeba  ziemanni.      T.c.    p.    620, 

7  figg.,  1903. 

36.  Sur  une  nouveau  Trypauosome  d'une  grenouille.    Op.  cit.  Ivii.  p.  158, 

2  figg.',  1904. 

37.  and  Mesnil,  F.     Recherches  morphologiques  et  experimentales  sur  le 

Trypanosome  des  rats,  Tr.  lewisi  (Kent).     Ann.  Inst.  Pasteur,  xv.  p.  673, 

2  pis.,  1901. 

38.  and Sur  les  Flagelles  a  membrane  ondulante  des  poissons  (genus 

Trypanosoma,  Gruby,  et  Trypanoplasma,  n.  gen.).     C.R.  Ac.  Sci.  cxxxiii. 
p.  670,  1901. 

39.  and  Sur  la  structure  du   Trypanosome  des  grenouilles  et  sur 

1'extension  du  genre  Trypanosoma,  Gruby.     C.R.  Soc.  Biol.  liii.  p.  678, 

3  figg.,  1901. 

40.  and Sur  les  Hematozoaires  des  poissons  marins.     C.R.  Ac.  Sci. 

cxxxv.  p.  567,  1902. 

41.  and  Sur  quelques  Protozoaires   parasites   d'une   tortue   d'Asie 

(Damonia  reevesii).     T.c.  p.  609,  14  figg.,  1902. 

42.  and Des  Trypanosomes  des  poissons.    Arch.  Protistenk.  i.  p.  475, 

15  figg.,  1902. 

43.  and   Recherches    morphologiques    et    experimentales    sur    le 

Trypanosome  du  Nagana  ou  maladie  de  la  mouche  tse-tse.     Ann.   Inst. 
Pasteur,  xvi.  p.  1,  13  figg.,  1902. 

44.  and Sur  un  Trypanosome  d'Afrique  pathogene  pour  les  Equides, 

T.  dimorphon,  Button  et  Todd.     C.R.  Ac.  Sci.  cxxxviii.  p.  732,  7  figg., 

45.  Lebailly,  C.     Sur  quelques  Hemoflagelles  des  Teleosteens  marins.     Op.  cit. 

cxxxix.  p.  576,  1904. 

46.  Lfyer,  L.     Sur  la  structure  et  la  mode  de  multiplication  des  Flagelles  du 

genre   Herpetomonas,    Kent.      C.R.    Ac.    Sci.    cxxxiv.    p.    781,    7   figg., 


47.  Ltger,  L.     Sur  un  Flagelle  parasite  de  1' Anopheles  mnculipennis.     C.R.  Soc. 

Biol.  liv.  p.  354,  10  figg.,  1902. 

48.  Sur  quelques  Cercomonadines  nouvelles  ou  peu  connues  parasites  de 

1'intestiu  des  Insectes.     Arch.  Protistenk.  ii.  p.  180,  4  figg.,  1903. 

49.  Sur  la  morphologie  du  Trypanoplasma  des  vairoiis,  et  sur  la  structure 

et  les  affinites  des  Trypauoplasmes.     C.R.  Ac.  Sci.  cxxxviii.   pp.  834, 
856,  5  figg.,  1904. 

50.   Sur  les  Hemoflagelles  du  Colitis  barbatula,  L.  ;  Trypanosma  barbatulae, 

n.  sp. ;  et  Trypanoplasma  varium,  n.  sp.    C.R.  Soc.  Biol.  Ivii.  pp.  344,  345, 

51.  Sur  tin  nouveau  Flagelle  parasite  des  Tabauids.     T.c.  p.  613,  6  figg., 


52. Sur  les  affinites   de  1' ' Herpetomonas  subulata  et  la  phylogenie  des 

Trypanosomes.      T.c.  p.  615,  1904. 

53.  Sur  la  presence  d'un    Trypanoplasma  intestinal   chez  les   poissons. 

Op.  cit.  Iviii.  p.  511,  1905. 

54.  Lignieres,   J.     Contribution   a   1'etude   de   la   trypanosomose   des    Equides 

Sud-Americains  connue  sous  le  nom  de  Mai  de  Caderas   (Trypanosoma 
elmassiani).     Rec.  Med.  Vet.  Bull,  et  Mem.    (8),  x.  pp.  51,  109,  164, 

2  pis.,  1903. 

55.  Lingard,  A.     A  new  Species  of  Trypanosome  found  in  the  Blood  of  Rats 

(India),  etc.     J.  Trop.  Vet.  Sci.  i.  p.  5,  1  pi.,  1906. 

56.  M'Neal,   W.  J.     On  the  Life-History  of   T.  lewisi  and  T.  brucii.     J.  Inf. 

Diseases,  i.,  Nov.  1904. 

57.  Minchin,  E.  A.     On  the  Occurrence  of  Encystation  in  Trypanosoma  grayi, 

Novy,  etc.     P.  Roy.  Soc.  Ixxix.  B,  p.  35,  text-figg.,  1907. 

58.  Investigations  on  the  Development  of  Trypanosomes  in  Tsetse-flies, 

etc.     Q.J.  Micr.  Sci.  Hi.  p.  159,  6  pis.,  1908. 

59.  ,  Gray,  A.  C.,  and  Tulloch,  F.  At.     Glossina  palpalis  in  its  Relation  to 

Trypanosoma  gambiense  and  other  Trypanosomes.    P.  Roy.  Soc.  Ixxviii.  B, 
p.  242,  3  pis.,  1906. 

60.  Mitrophanow, .   Beitrage  zur  Kenntniss  der  Hamatozoen.    Biol.  Centrlbl. 

iii.  p.  35,  2  figg., '1883. 
61;  Novy,  F.  G.     The  Trypanosomes  of  Tsetse-flies.     J.  Inf.  Diseases,  iii.  p.  394, 

3  pis.,  1906. 

62.  and  M'Xeal,  W.  J.     On  the  Trypanosomes  of  Birds.     Op.  cit.  ii.  p.  256, 

11  pis.,  1905. 
63. and  —    -    On  the  Cultivation  of  Trypanosoma  brucii.     Op.  cit.  i.  p.  1, 

64. , ,    and    Torrey,    H.  N.     The   Trypanosomes   of  Mosquitoes  and 

other  Insects.     Op.  cit.  iv.  p.  223,  7  pis.,  1907. 

65.  Patton,  W.  S.     Preliminary  Note  on  the  Life-Cycle  of  a  Species  of  Herpeto- 

monas found  in  Culex pipiens.     B.M.J.,  1907,  ii.  (July  13th). 

66.  Plchn,  M.     Trypanoplasma  cyprini,  n.  sp.    Arch.  Protistenk.  ii.  p.  175,  1  pi., 


67.  Pricolo,  A.    Le  Trypanosome  de  la  souris.    Cycle  de  developpement  des  Try- 

panosomes chez  le  fetus.     Centralbl.  Bakt.,  Abt.  1,  xlii.  Orig.  p.  231,  1906. 

68.  Prowazek,      S.       Studien     iiber     Saugethiertrypanosomen.       Arb.     kais. 

Gesundhtsa.  xxii.  p.  1,  6  pis.,  1905. 

69.  Die  Eutwickelung  von  Herpetomonas,  einen  mit  den  Trypanosomen 

verwandten  Flagellaten.     Op.  cit.  xx.  p.  440,  text-figg.,  1904. 


70.  Rabinowitsch,    L.,    and     Kempner,      W.       Beitrage    zur     Kenntniss     der 

Blutparasiten,  speciell   der   Rattentrypanosomen.      Zeitschr.  Hyg.  xxx. 
p.  251,  1  pi.,  1899. 

71.  Robertson,  M.     Notes  on  Certain  Blood-inhabiting  Protozoa.     Proc.  Physic. 

Soc.  Edinb.  xvi.  p.  232,  2  pis.,  1906. 

72.  Studies  on  a  Trypanosome  found  in  the  Alimentary  Canal  of  Ponlob- 

della  muricata.     Op.  cit.  xvii.  p.  83,  4  pis.,  1907. 

73.  Rogers,  L.     The  Transmission  of  the  Trypanosoma  eransi  in  India  by  Horse- 

flies, etc.     Proc.  Roy.  Soc.  Ixviii.  p.  163,  1901.     Also  see  B.M.J.,  1904, 
ii.  p.  1454. 

74.  Ross,  11.     Notes  on  the  Parasites  of  Mosquitoes  found  in  India  between  1895 

and  1899.     Journ.  Hyg.  vi.  p.  101,  1906. 

75.  Schaudinn,   F.     Generations-    uud   Wirthswechsel   bei   Trypanosoma    und 

Spirochaeta.     Arb.  kais.  Gesundhtsa.  xx.  p.  387,  text-figg.,  1904. 

76.  Sergent,  E.  and  E.     Sur  un  Trypanosome  nouveau  parasite  de  la  grenouille 

verte.     C.R.  Soc.  Biol.  Ivi.  p.  123,  1  fig.,  1904. 

77.  Hemamibes  des  oiseaux  et  moustiques.      Generations  alternantes  de 

Schaudinn.     Op.  cit.  Iviii.  p.  57,  1905. 

78.  Sur  des  Trypanosomes   des   chauves  -  souris.       T.c.   p.    53,   2  figg., 


79.  Sur  un  Flagelle"  nouveau  de  1'intestin  des  Culex  et  des  Stegomyia, 

Herpetomonas  algeriense.     Op.  cit.  Ix.  p.  291,  1906. 

80.  Stuhlmann,  F.     Beitrage  zur  Kenntniss  der  Tsetsefliegen  (Gl.  fusca  and  Gl. 

tachinoides).     Arb.  kais.  Gesundhtsa.  xxvi.  p.  83,  4  pis.,  1907. 

81.  Swingle,  L.  D.     Some  Studies  on  Trypanosoma  lewisi.     Trans.  Amer.  Micr. 

Soc.  xxvii.  p.  Ill,  1  pi.,  1907. 

82.  Thiroux,  .     Sur  un  nouveau  Trypanosome  des  oiseaux.     C.R.  Ac.  Sci. 

cxxxix.  p.  145,  5  figg.,  1904. 

83.  Recherches  morphologiques  et  experimentales  sur  les   Trypanosoma, 

paddae.     Ann.  lust.  Pasteur,  xix.  p.  65,  1  pi.,  1905. 

84.  Recherches  ...  sur  Trypanosoma  duttoni,  Thiroux.      T.c.   p.  564, 

1  pi.,  1905. 

85.  Voges,  0.     Mai  de  Caderas.     Zeitschr.  Hyg.  xxxix.  p.  323,  1  pi.,  1902. 

86.  Wasielewsky  and  Senn,  G.      Beitrage  zur  Kenntniss  der  Flagellaten  des. 

Rattenblutes.     Op.  cit.  xxxiii.  p.  444,  3  pis.,  1900. 

II.  Relating  to  the  ' '  Leishman- Donovan-  Wright "  Bodies. 

87.  Christophers,  S.  R.     Reports  on  a  Parasite  found  in  Persons  suffering  from 

Enlargement  of  the  Spleen  in  India.     Sci.  Mem.  India,  Nos.  8,  11,  15, 

88.  Donovan,  C.     Human  Piroplasmosis.     Lancet,  1904,  ii.  p.  744,  1  pi. 

89.  James,  S.  P.     Oriental  or  Delhi  Sore.     Sci.  Mem.  India,  No.  13,  1905. 

90.  Laveran,  A.,   and   Mesnil,  F.     Sur   un   Protozoaire   nouveau   (Piroplasma 

donovani,  Lav.  et  Mesn.),  etc.     C.R.  Ac.  Sci.  cxxxvii.  p.  957,  17  figg., 
1903  ;  and  op.  cit.  cxxxviii.  p.  187,  1904. 

91.  Leishman,  W.     On  the  Possibility  of  the  Occurrence  of  Trypanosomosis  in 

India.     Brit.   Med.  Journ.   1903,   i.   p.    1252,  2  figg.  ;   see  also  op.  cit., 
1904,  i.  p.  303. 

92.  and    Statham.       The     Development    of    the    Leishman     Body    in 

Cultivation.     Journ.  Army  Med.  Corps,  iv.  p.  321,  1  pi.  2  figg.,  1905. 


93.  Patton,    W.  S.     Prelim.    Report   on  the  Development  of  the  Leishman- 

Donovan  Body  in  the  Bed-Bug.     Sci.  Mem.  India,  No.  27,  1907. 

94.  Rogers,  L.    On  the  Development  of  Flagellated  Organisms  .  .   .  from  the 

Spleen  Protozoic  Parasites  of  Kala-Azar.     Q.J.  Micr.  Sci.  xlviii.  p.  367, 
1  pi.,  1904. 

95.  Further  Work  on  the  Development  of  the  Herpetomonas  of  Kala- 
Azar  .  .  .  from  the  Leishmau-Donovan  Bodies.    Proc.  Roy.  Soc.  Ixxvii.  B, 
p.  284,  pi.  7,  1906  ;  see  also  Lancet,  1905,  i.  p.  1484. 

96.  floss,  It.     A  New  Parasite  of  Man.     Thorn pson-Yates  Lab.  Rep.   (5),  2, 

p.  79,  1  pi.,  1904. 

97.  Wright,  J.  H.     Protozoa  in  a  Case  of  Tropical  Ulcer  (Delhi  Sore).     Journ. 

Med.  Research,  Boston,  x.  p.  472,  4  pis.,  1903. 

C.  Relating  to  the  Spirochaetae. 

98.  Certes,  A.     Note  sur  les  parasites  et  les  commensanx  de  1'huitre.     Biol. 

Soc.  Zool.  France,  vii.  p.  347,  1  pi.,  1882  ;  see  also  op.  cit.  xvi.  pp.  95  and 
130,  1891. 

99.  Laveran,  A.,  and   Mesnil,   F.     Sur  la   nature   bacterienne   du   pretendu 

Trypauosome  des  huitres,  "  T."  balbianii.     C.R.  Soc.  Biol.  liii.  p.  883, 

100.  Perrin,    W.  S.     Researches  upon   the   Life -History  of   "  Trypanosoma " 

balbianii  (Certes).      Arch.   Protistenkunde,    Jena,   vii.    p.   131,    2   pis., 

101.  Krzysztalowicz,  F.,  and  Siedlecki,  M.     Contribution  a  1'etude  de  la  struc- 

ture  et  du  cycle  evolutif  de   Spirochaeta  pallida,  Schaud.     Bull.    Ac. 
Cracovie,  1905,  p.  713,  1  pi. 

102.  Schaiulinn,  F.     Zur  Kenntniss  der  Spirochaeta  pallida.     Deutsch.   med. 

Wochenschr.    No.    42,    1905,    p.    1665  ;    see    also    t.c.    p.    1728    (gen. 
Treponeina  proposed). 

103.    and    Hoffmann,   E.     Vorlaufiger    Bericht   ueber   das    Vorkommen 

von   Spirochaeten   in   syphilitischen    Krankheitsproducten.      Arb.    kais. 
Gesundhtsa.  xxii.  p.  527,  1905. 



THIS  genus  is  represented  by  two  species.  C.  labyrinthuloides  was  dis- 
covered by  Archer  in  pools  in  moorland  country  in  Ireland  and 
described  by  him  in  1875  (1).  It  has  subsequently  been  investigated 
by  Geddes  (2)  in  material  supplied  by  Archer  ;  and  by  Hieronymus  (3), 
who  found  it  in  the  Riesengebirge  and  elsewhere  in  Germany.  0.  mon- 
tana  was  first  described  by  Lankester  (5)  and  obtained  by  him  in 
Sphagnum  swamps  in  Switzerland,  and  has  since  been  investigated  by 
Penard  (6). 

Two  main  phases  of  the  life-history  are  in  many  respects  well 
known — a  free  active  stage,  with  pseudopodia  more  or  less  extended,  and 
a  (much  commoner)  encysted  stage  ;  and  we  now  have  evidence,  though 
it  is  still  incomplete,  of  stages  of  multiplication  by  fission  and  of  spore- 

Chlamydomyxa  unites  in  a  remarkable  manner  the  holophytic  and 
holozoic  modes  of  nutrition.  The  protoplasmic  body  is  crowded  with 
chromatophores,  by  means  of  which  it  is  able  to  increase  largely  in  size  in 
the  encysted  state  ;  but  it  is  also  able,  in  its  active  phase,  to  engulf  and 
to  digest  animal  and  vegetable  organisms. 

The  body  consists  of  hyaline  protoplasm  containing  nuclei,  chromato- 
phores, and  small  refracting  bodies — the  "oat-shaped  corpuscles"  of 
Lankester.  In  the  encysted  condition  it  may  form  a  globular  mass, 
measuring,  when  fully  grown,  60-90  p  in  diameter  in  C.  labyrinthuloides, 
the  cysts  of  C.  montana  being  a  little  smaller. 

The  nuclei  (Fig.  1,  a,  b,  and  d)  vary  from  1  '5  to  3  //,  in  diameter.  They 
are  generally  evenly  distributed  through  the  protoplasm,  and  they  increase 
in  number  with  its  growth.  In  the  large  cysts  of  C.  labyrinthuloides 
there  may  be  as  many  as  32  or  more  ;  in  C.  montana,  according  to  Penard, 
100  or  more.  They  contain  a  nucleolus  or  group  of  nucleoli  at  the 
centre,  and  there  are  indications  of  a  nuclear .  reticulum  at  the  periphery. 
Their  mode  of  division  is,  according  to  Hieronymus,  intermediate  between 
mitosis  and  amitosis.  In  life  they  are  visually  hidden  by  the  chromato- 
phores, and  thus  escaped  the  notice  of  the  earlier  observers. 

The  chromatophores  are  oval  bodies  varying  in  size  up  to  3  //,  (C.  mon- 
tana) and  5'5  /A  (G.  labyrinthuloides,  Fig.  1,  d).  They  consist  of  coloured 

1  By  J.  J.  Lister,  M.A.,  F.R.S.,  Fellow  of  St.  John's  College,  Cambridge. 




and  colourless  tracts,  which  are  apparently  differently  distributed  in  the  two 
species.  The  colour  varies  from  grass-green  to  olive-green,  yellow,  and 
brown,  and  is  dependent  on  the  presence,  in  varying  proportions,  of 
chlorophyll  and  of  a  yellow-brown  colouring  matter  (?  diatomin).  They 


PIG.  1. 

Chlamydomyxa  labyrinthuloides.  a  and  6,  cysts  from  leaf-cells  of  Sphagnum,  constricted  by 
the  characteristic  annular  bands  of  the  latter,  from  stained  preparations  showing  the  chromato- 
phores and  nuclei,  x  620.  c,  end  of  a  living  cyst,  treated  with  weak  methylene  blue  solution. 
The  chromatophores  are  shaded.  The  nuclei  are  not  seen,  x  5000.  d,  nuclei  highly  magnified  ; 
c,  /,  living  chromatophores ;  g,  chromatophore  after  treatment  with  Flemming's  fluid  and 
fuchsin  ;  h,  oat-shaped  corpuscles  ;  e-h  x  about  10,000.  (After  Hieronymus.) 

appear  to  multiply  by  binary  fission  (Fig.  I,/).  The  absence  of  a  cellulose 
envelope  and  of  a  nucleus,  as  well  as  other  characters  of  the  chromatophores, 
prevent  their  being  regarded  as  symbiotic  algae.  As  a  degeneration 
product,  and  especially  under  the  influence  of  bright  sunlight,  the 
colouring  matter  breaks  down,  producing  a  red  or  brown  fatty  substance 
^lipochrome)  which  accumulates  in  drops  in  the  interior  of  the  cysts,  and, 


by  its  colour,  reveals  the  presence  of  Chlamydomyxa  when  it  is  present  in 
abundance  on  the  vegetation  of  a  pool. 

The  oat-shaped  corpuscles  ("spindles"  of  Archer,  "physodes"  of 
Hieronymus)  are  shining,  highly-refracting  bodies,  homogeneous  or  faintly 
laminated,  of  a  pale  bluish  tint  and  semifluid  consistence  (Fig.  1,  h). 
They  are  round  or  oval  in  shape,  but  become  longer  (oat-shaped)  when 
drawn  out  on  the  pseudopodial  filaments.  They  vary  in  size  up  to  about 
2  p.  in  length.  As  regards  composition,  Hieronymus  identifies  them  with 
phloroglucin,  a  member  of  the  aromatic  series  which  occurs  in  the 

When  Chlamydomyxa  was  discovered  the  resemblance  between  these 
bodies,  held  in  the  expanded,  stiff  pseudopodial  network  (Fig.  3  (2))  and 
the  nucleated  units  of  the  associations  of  Labyrinthula,  suggested  the  view 
that  they  might  be  of  similar  nature,  although  nothing  of  a  nuclear 
character  could  be  revealed  in  the  corpuscles  by  stains,  and  they  are, 
moreover,  much  smaller  than  the  units  of  Labyrinthula.  The  evidence 
which  we  now  have  as  to  the  nuclei  of  Chlamydomyxa,  and  as  to  the 
chemical  nature  of  these  bodies,  prevents  our  acceptance  of  this  view. 
They  are  probably  to  be  regarded  as  reserve  food  material  (possibly  in 
relation  with  the  metabolism  of  cellulose)  stored  in  a  granular  form. 

Crystals  of  oxalate  of  lime,  formed  doubtless  in  the  katabolic  pro- 
cesses, are  also  present  in  the  cell-fluids,  and  they  may  be  crowded  in 
vacuoles  of  the  encysted  animal,  to  be  expelled  when  it  emerges. 

The  cysts  of  Chlamydomyxa  are  found  in  great  abundance  within  the 
large  cells  of  the  leaves  of  Sphagnum,  or  between  the  cells  of  other 
aquatic  plants  (Hypnum,  Eriocaulon,  cotton-grass,  etc.).  They  may  also 
be  found  on  the  surface  of  these  and  other  submerged  bodies. 

They  are  invested  by  a  cellulose  envelope,  often  consisting  of  several 
laminae  added  one  within  another,  and  the  investment  appears  to  be  of  a 
plastic  consistency,  expanding  with  growth  so  as  to  cover  large  protrusions 
of  the  cyst  which  extend  through  apertures  in  the  cell-wall,  and  it  may 
close  in  about  portions  which  are  withdrawn  from  deeper  recesses  of  the 
plant  tissue.  Considerable  growth  of  the  protoplasmic  body  may  occur 
in  the  encysted  condition,  a  result  dependent  on  the  holophytic  nutrition 
brought  about  by  the  agency  of  the  chromatophores.  The  youngest 
cysts  found  in  a  Sphagnum  leaf  are  very  small  and  contain  a  single 
nucleus.  As  they  increase  in  size  and  become  limited  by  the  walls  of  the 
elongated  leaf-cells  they  grow  in  length  (Fig.  1,  a  and  6).  The  cysts  may 
finally  break  through  the  wall  of  the  cell  and  project  in  lobate  prominences 
to  the  exterior.  The  activities  of  the  encysted  organism  do  not,  however, 
result  in  uniform  growth,  for  many  cysts  have  shrunken  contents,  and 
have  formed  a  fresh  wall  separate  from  the  original  one,  and  in  the 
space  between  the  envelopes  groups  of  the  red  oil- globules  referred  to 
above  may  lie,  discharged  before  the  inner  wall  was  secreted.  Moreover, 
the  contents  of  a  cyst  may  undergo  division  within  the  envelope  into  two 
or  more  parts,  and  each  part  then  forms  a  wall  of  its  own. 

When  the  cysts  are  fully  grown  and  favourable  conditions  occur,  an 
aperture  is  formed  in  the  envelope,  presumably  by  the  solvent  action  of 
the  protoplasm  on  the  cellulose,  and  the  contents  emerge  in  the  free  state. 


The  accounts  of  the  behaviour  of  the  organism  in  the  free  state  differ 
considerably  and  are  not  easy  to  reconcile. 

In  G.  labyrintJmloides,  as  described  by  Archer  (cp.  his  figure  in  the 
Q.J.M.S.  vol.  xv.  Plate  vi.,  from  which  Fig.  3  (2)  is  taken),  the  proto- 
plasmic body  was  still  partially  contained  in  the  cyst.  Extending 
through  the  aperture,  it  was  produced  into  a  dendriform  system  of 
branches,  diminishing  in  thickness.  From  the  ends  and  sides  of  the 
branches  filiform  hyaline  pseudopodia  of  small  but  uniform  thickness 
reach  far  out  into  the  water.  The  chromatophores  are  not  seen  in 
relation  with  the  filaments,  but  these  are  plentifully  beset  with  the  oat- 
shaped  corpuscles.  The  latter  are  drawn  out  in  the  direction  of  the 
filament,  and  slowly  travel  along  it  in  one  direction  or  the  other.  The 
filaments  are  sparingly  branched ;  whether  or  not  they  anastomose, 
observers  are  not  agreed.  They  have  a  "  stiff  but  flexible "  (Penard) 
consistency.  Lankester  is  inclined  to  regard  the  filaments  as  "  inert 
products  of  the  metamorphosis "  of  the  protoplasm,  over  which  a 
"  delicate  varnish "  of  hyaloplasm  extends,  investing  the  corpuscles  and 
carrying  them  along  in  its  flow.  Yet  the  whole  system  of  these 
remarkable  pseudopodia  can  be  rapidly  withdrawn  into  the  general  mass 
when  the  animal  is  disturbed.  Hieronymus  describes  a  peculiar  fibrous 
arrangement  of  the  protoplasm  even  in  the  encysted  state,  which  may  be 
in  relation  with  the  peculiar  characters  of  the  extended  filaments  (Fig.  1,  c. 
Note  the  linear  arrangement  of  the  oat-shaped  corpuscles). 

Contractile  vacuoles  abound  in  the  extended  protoplasmic  body. 
Their  period  probably  varies  with  its  activity.  In  0.  montana  Penard 
finds  it  to  be  very  slow. 

In  the  active  condition  C'hlamydomyxa  is  able  to  engulf  and  digest 
algae,  desmids,  Peridinidae,  etc.,  and  outlying  masses  of  protoplasm  may 
be  seen  (Fig.  3  (2))  accumulated  about  such  food-bodies. 

The  accounts  of  the  active  phase  of  0.  montana  agree,  on  the  whole, 
with  Archer's  observations  of  G.  labyrinthuloidcs,  except  that  in  the 
former  species  the  protoplasm,  on  emerging,  completely  quits  the  old  cyst- 
wall  and  lies  free  in  the  water  as  a  mass  of  constantly  changing  shape. 
It  may  be  more  or  less  spherical  or  drawn  out  into  a  ribbon,  attaining  a 
length  of  300  p,  (Penard).  A  definite  hyaline  ectoplasm  is  also  present. 
(Cp.  the  figures  of  this  species  given  by  Lankester,  Q.J.M.S. 
vol.  xxxix.  Plates  xiv.  and  xv.)  In  it,  moreover,  the  yellow  colouring 
matter  of  the  chromatophores  usually  predominates  over  the  green. 

According  to  most  observers,  the  free  state  of  the  organism  would 
appear  to  end,  after  lasting  at  least  "  several  hours,"  by  the  withdrawal  of 
the  extended  protoplasm  and  the  re-encystment  of  the  whole  animal. 
Hieronymus  differs  considerably  from  other  observers  in  his  account  of 
the  free  state.  He  has  also  seen  the  contents  emerge  from  a  cyst  of 
C.  labyrinthuloides,  assume  an  irregular  amoeboid  form,  and  ingest  food 
"auf  thierische  Weise"  ;  but  it  is  remarkable  that  he  has  never,  during 
the  twelve  years  over  which  his  observations  have  extended,  seen  the  long 
filamentary  pseudopodia  protruded  in  the  manner  which  has,  in  both 
species,  attracted  attention.  The  nearest  approach  to  such  filaments 
which  he  has  seen  were  those  of  a  small  specimen  suspended  free  in  the 


water  and  emitting  long  pseudopodia  on  all  sides  (3  ;  Plate  ii.  Fig.  25). 
After  ingesting  food  the  animals  were  found  by  Hieronymus  to  encyst  on 
the  surface  of  plants,  and  he  states  that  division  of  the  nuclei  follows  the 
encystment.  But  in  the  majority  of  cases  a  different  process  was 
observed  to  follow  the  emergence  from  the  encysted  state.  The  proto- 
plasm puts  out  short  pseudopodia  and  divides  up  forthwith,  by  successive 
repartition  or  by  simultaneous  division,  into  small  uninucleate  amoebae, 
the  products  of  division  being  equal  in  number  to  the  nuclei  contained 
in  the  original  cyst.  The  division  into  the  ultimate  products  is  usually 
complete  in  a  few  minutes  from  the  emergence  of  the  protoplasm.  The 
small  amoebae  so  found  may  creep  about  and  ingest  small  algae  or 
bacteria  before  passing  into  the  encysted  form.  While  this  is  the  usual 
course,  Hieronymus  describes  cases  in  which  the  process  of  division  ceased 
after  one  or  two  partitions  had  occurred,  and  was  followed  by  a  stage  of 
feeding  and  subsequent  encystment.  Further  evidence  of  such  cases 
would  be  desirable,  and  it  seems  possible  that  two  separate  phases  of  the 
life-history  may  have  been  here  confused ;  but  it  is  clear  that  the  fission 
of  the  multinucleate  body  into  uninucleate  products  represents  a  phase  of 
reproduction  comparable  with  that  which  occurs  in  many  other  protozoan 
life-histories,  and  of  which  we  had  no  previous  evidence  in  Chlamydomyxa. 

Spore-Formation. — The  process  of  spore-formation  has  been  most  fully 
observed  by  Penard  in  G.  montana,1  but  stages  of  it  have  been  seen  by 
Archer  and  Hieronymus  in  C.  labyrinthuloides.  The  contents  of  an 
encysted  form  are  segregated  by  simultaneous  fission  into  a  number 
(20  to  40)  of  equal  (Fig.  2,  a)  (?  sometimes  only  sub-equal  (Fig.  2,  6)) 
divisions.  These  are  at  first  continuous  with  their  neighbours  by  proto- 
plasmic strands  (3  ;  Plate  i.  Fig.  7),  but  later  they  separate  into  bodies 
which  become  spherical  and  each  secretes  a  cellulose  wall.  They  are 
liberated  by  the  opening  of  the  cyst  (in  a  manner  not  observed).  Penard 
finds  that  these  secondary  cysts,  or  spores  (Fig.  2,  c),  as  we  may  call  them, 
measure  in  G.  montana  18  [L  in  diameter,  and  that  each  contains  two 
nuclei  lying  opposite  one  another  in  a  meridian  of  the  sphere.2  In  some 
cases  the  contents  of  the  spores  were  found  to  have  emerged  as  naked 
masses  of  protoplasm,  containing  the  chromatophores  and  refracting 
corpuscles  characteristic  of  the  species.  Each  acquired  a  flagellum  (or  two 
flagella  ?)  about  equal  to  the  body  in  length  (Fig.  2,  d),  and  for  some 
moments  ("pour  quelques  instants")  was  actively  motile.  Some  of  these 
flagellate  bodies  appeared  to  possess  one  nucleus,  others  two  or  even 
three,  and  there  was  an  indication  of  their  fusion  in  pairs  ("  lorsque  les 
petits  flagellates  viennent  &  se  rencontrer,  ils  peuvent  se  fusionner  en  un 
seul,"  p.  331).  Some  continued  to  show  a  slow  movement  for  twenty- 
four  hours,  but  ultimately  they  died  under  the  cover-slip. 

It  would  be  premature  at  present  to  make  any  dogmatic  statement  as 

1  It  was  only  for  a  few  days  that  Penard  succeeded  in  observing  this  stage  in  the 
life-history.     It  occurred  in  March,  in  the  neighbourhood  of  Geneva. 

2  Penard's  account  of  the  subsequent  history  of  these  bodies  is  of  great  interest, 
but,  owing  to  the  sparseness  of  his  rnaterial  and  the  rapidity  of  some  of  the  events, 
he  was  unfortunately  not  able  to  observe  the  stages  with   precision.      With  this 
reserve,  an  outline  of  his  results  is  here  given. 



to  the  course  of  the  life-history  of  Chlamydomyxa.  The  observations 
of  Penard  suggest  that  the  flagellulate  bodies  hatching  from  the  spores 
are  gametes,  which  proceed  to  conjugate  with  one  another,  though  the 
existence  of  two  nuclei  in  the  spores  requires  explanation.  If  this  is  the 
case,  we  have,  as  in  Trichospliaerium  and  many  other  Protozoa,  a  life-cycle 
in  which  a  sexual  phase  recurs  in  a  series  of  generations  reproducing  by 

With  regard  to  the  affinities  of  Chlamydomyxa,  we  have  seen  that  the 
resemblance  to  Labyrinthula  turns  out  to  be  in  part  at  least  misleading. 


FIG.   2. 

CMa»rt  >/<'"»>•/"'.  a.  Early  stage  of  spore-formation  in  C.  montana.  The  contents  of  a  cyst 
have  become  divided  up  into  young  spores  ;  b,  a  cyst  of  C.  labyrinthuloides,  with  mature  spores, 
x  200 ;  c,  a  single  spore  of  C.  montana,  showing  two  nuclei ;  d,  flagellate  body  hatched  from 
a  spore.  ('<,  <•,  ami  il  after  Penard  ;  6  after  Archer.) 

We  are  unable  to  agree  with  Penard  that  it  is  allied  to  the  Mycetozoa, 
for  there  is  no  evidence  that  the  protoplasmic  masses  are  plasmodia  in 
the  true  sense  of  the  term.  It  appears  that  the  most  satisfactory  position 
to  assign  to  it,  in  the  present  preliminary  stage  of  our  knowledge  of  life- 
liistories,  is  as  an  isolated  rhizopod,  containing  chromatophores,  which 
may  be  provisionally  placed  in  the  neighbourhood  of  the  freshwater  forms 
with  filose  pseudopodia  which,  in  this  work,  are  included  in  the  Order 
Gromiidea  of  the  Foraminifera  (see  p.  283).  In  the  possession  of  many 
nuclei  it  resembles  Trichosphaerium  among  the  Rhizopoda  Lobosa. 


1.  Archer,  W.  On  Chlamydomyxa  labyrinthuloides,  nov.  gen.  et  sp.,  a  New 
Freshwater  Sarcodic  Organism.  Quart.  Journ.  Micr.  Sci.  N.S.  xv. 
(1875),  p.  107. 


2.  Gcddes,   P.     Observations   on   the  Resting  State   of  Chlamydomyxa  laby- 

rinthuloides,  Archer.     Ibid.  xxii.  (1882),  p.  30. 

3.  Hieronymus,    G.       Zur    Kenntniss    von    Chlamydomyxa    labyrinthuloides, 

Archer.     Hedvvigia,  Bd.  xxxvii.  (1898),  p.  1. 

4.  Jenkinson,  J.  W,    Abstract  and  Review  of  the  above  paper  by  Hieronyimis. 

Quart.  Journ.  Micr.  Sci.  N.S.  xlii.  (1899),  p.  89. 

5.  Lankester,  E.  Ray.      Chlamydomyxa  monta'iia,  n.  sp.,  one  of  the  Protozoa 

Gyranomyxa.     Quart.  Journ.  Micr.  Sci.  xxxix.  (1896),  p.  233. 

6.  Penard,  E.  Etude  sur  la  Chlamydomyxa  montana.    Arch.  f.  Protistenkunde, 

Bd.  iv.  Heft  2  (1904),  p.  296. 


The  members  of  this  genus  consist  of  associations  of  nucleated  proto- 
plasmic units  ("amoebae"  of  Zopf,  "spindles"  of  Cienkowski)  joined  in 
a  network  of  sparingly  branched  and  anastomosing  threads.  They  are 
met  with  in  a  diffuse  or  aggregated  condition,  and,  as  the  result  of 
drying,  the  units  pass  into  a  condition  of  encystment,  from  which  they 
hatch  out  in  the  form  of  the  amoeboid  units. 

Two  marine  species  were  described  in  1867  by  Cienkowski  (1),  who 
found  them  on  algae  growing  on  wooden  piles  in  the  harbour  of  Odessa : 
L.  vitellina,  Cienk.,  in  which  the  protoplasmic  units  contain  a  yellow  or 
orange  colouring  matter  ;  and  L.  macrocystis,  Cienk.,  in  which  the  units 
are  larger  and  colourless.  Zopf  (4)  in  1892  described  a  freshwater 
form  very  similar  to  L.  macrocystis,  parasitic  on  the  alga  Vaucheria. 
He  named  it  L.  cienkowskii,  Zopf. 

In  the  marine  forms  the  system  of  connecting  threads  appears  to  have 
a  remarkably  firm  and  rigid  consistency,  and  Cienkowski  describes  the 
movement  of  the  units  along  the  threads,  as  though  the  latter  were 
peculiarly  differentiated  structures  ;  but  from  Zopf's  description  of  L. 
cienkowskii  it  can  hardly  be  doubted  that  they  are  pseudopodial  in  nature. 
Zopf  observed  them  to  be  slowly  protruded  from  a  mass  of  units,  and  to 
be  withdrawn,  to  move  slowly  from  side  to  side,  and  to  fuse  with  their 
neighbours.  He  also  describes  the  passage  of  food  -  granules  along 

The  units  are  without  a  limiting  membrane  and  contain  a  single 
nucleus,  with  a  nucleolus.  When  drawn  out  in  the  expanded  condition 
of  the  organism  they  are  generally  spindle-shaped  (Fig.  3  (3)),  but  they 
may  present  processes  in  three  directions  (Fig.  3  (4)).  In  the  aggregated 
condition  the  units  are  round  or  oval.  Those  of  L.  macrocystis  measure 
18-25  fj,  in  long  diameter,  those  of  L.  vitellina  and  L.  cienkowskii  about 
1 2  /*.  The  protoplasm  is  granular,  and  in  L.  vitellina  contains  a  yellow 
or  orange  fatty  pigment,  soluble  in  alcohol.  A  small  vacuole  is  usually 
present,  but  it  is  not  stated  that  it  is  contractile. 

The  whole  organism,  or  a  part  of  it,  is  often  found  in  the  aggregated 
condition  (Fig.  3  (5)),  and  the  marine  species  may  thus  form  masses 
measuring  a  millimetre  or  so  in  diameter.  The  main  aggregate  is 
described  by  Cienkowski  as  invested,  in  L.  vitellina,  by  a  "  cortical  sub- 
stance" (neither  protoplasmic  nor  of  the  nature  of  cellulose)  through 


which  the  filaments  are  protruded,  but  this  was  not  seen  in  the  peripheral 
aggregates  of  this  species,  nor  at  all  in  the  active  condition  of  the  other 

Labyrinthula  is  actively  parasitic  on  the  algae  which  it  infests, 
breaking  down  the  contents  of  the  cells  into  a  granular  mass. 

As  the  result  of  drying,  the  organism  passes  into  a  condition  of 
encystment.  The  units  became  closely  aggregated  and  each  secretes  a  cyst- 
wall,  which  is  double  in  L.  cienkowskii.  A  firm  common  envelope  may 
now  be  formed  (in  L.  macrocystis,  Fig.  3  (5),  but  not  in  other  species)  in 
which  the  encysted  units  are  embedded. 

The  behaviour  of  the  encysted  unit  appears  to  vary  in  the  different 
species.  In  L.  cienkowskii  Zopf  describes  and  figures  the  emergence  of  a 
single  mass  from  the  cyst.  In  the  other  species,  Cienkowski  found  that  the 
contents  divided  into  four  within  the  cyst  (Fig.  3  (6  and  7)).  Zopf  observed 
the  protrusion  of  one  or  two  long  pointed  pseudopodia,  on  hatching,  and 
the  final  emergence  of  the  protoplasmic  mass  from  the  cyst,  which  was 
left  empty.  From  the  fact  that  on  one  occasion  three  empty  cases  were 
found  with  three  units  in  their  neighbourhood,  and  that  these  were  in 
connection  by  their  pseudopodia,  Zopf  concludes  that  the  hatched  units 
join  with  one  another  to  start  a  fresh  association. 

Zopf  regards  the  association  of  units  of  Labyrinthula  as  representing 
a  stage  in  the  formation  of  a  plasmodium  intermediate  between  the  true 
•plasmodium  of  the  Euplasmodida  (cf.  p.  43),  in  which  there  is  a  complete 
fusion  between  the  protoplasmic  bodies  of  the  uniting  amoebulae,  and  the 
pseudoplasmodium  of  the  Sorophora,  in  which  the  amoebulae,  aggregating 
before  spore-formation,  come  into  apposition  but  maintain  their  distinct- 
ness (p.  60).  This  intermediate  form  he  would  distinguish  as  a  Thread- 
-plasmodium  (Fadenplasmodium). 

The  propriety  of  this  view  seems  far  from  clear.  We  are  familiar 
•with  many  cases  among  Protozoa  in  which  an  association  of  individuals, 
a.  colonial  organism,  is  formed  by  the  successive  multiplication  of  the 
units,  whose  offspring  remain  in  connection  by  protoplasmic  processes 
(Colonial  Radiolaria,  Volvox,  Mikrogromio),  and  the  higher  animals  and 
plants  are  often  regarded  as  such  colonial  organisms,  in  modified 

That  an  increase  in  the  number  of  units  in  the  associations  of  Laby- 
rinthula occurs  by  binary  fission  of  the  units  is  abundantly  clear.  It  is 
true  that  it  appears  probable,  from  Zopfs  observation  above  quoted,  that 
a  fusion  may  occur  in  Labyrinthula  (though  it  was  not  actually  observed) 
between  the  pseudopodia  of  individuals  recently  emerged  from  the 
•encysted  state  ;  but  a  parallel  to  this  process  may  be  found  in  the 
fusion  of  the  protoplasmic  masses  emerging  from  the  cysts  of  the 
sclerotial  condition  of  the  Mycetozoa  on  revival  of  activity  (cp.  p.  50). 
There  are  fair  grounds  for  regarding  the  fusion  of  the  amoebulae 
by  which  the  Mycetozoan  plasmodium  takes  its  origin  (in  the  Euplas- 
modida) as  a  part,  at  any  rate  the  plastogamic  part,  of  a  sexual  union  of 
which  the  final,  karyogamic,  stage  is  deferred.  It  would  not  be  sug- 
gested that  the  fusion  after  the  sclerotial  stage  is  a  repetition  of  this 
process  in  the  Mycetozoa,  and  we  may  well  hesitate,  in  the  present 


FIG.  3. 


fragmentary  state  of  our  knowledge  of  Labyrinthula,  to  accept  the  conclu- 
sion that  the  (inferred)  fusion  between  the  pseud  opodia  after  encystment 
represents  this  important  event  in  its  life-history. 

We  are  therefore  inclined  to  regard  Labyrinthula  as  a  colonial 
organism  of  which  the  units  remain  in  connection  by  their  pseudopodia. 
As  the  result  of  drying  they  may  pass  into  the  encysted  stage,  in  which 
they  are  isolated  from  their  fellows  by  the  cyst-walls.  It  appears  prob- 
able, from  Zopfs  observation,  that,  on  resuming  activity,  they  may 
again  unite  with  their  fellows  to  form  a  colony.  Other  stages  of  the 
life-history  are  at  present  unknown  to  us. 

With  Labyrinthula  Zopf  associates  the  genus  Diplophrys  (Archer), 
Cienk.  The  species  named  Diplophrys  stercorea  by  Cienkowski  (2)  is  a 
colonial  organism,  with  simple  thread-like  pseudopodia,  living  on  horse- 
dung.  It  can  hardly  belong  to  the  same  genus  as  Diplophrys  Archeri 
(Barker),  with  ramifying  pseudopodia  and  a  distinct  though  membranous 

FIG.  3. 

2.  CMamydomyxa  Ifihyrinthuloldes,  Archer.  The  animal  in  the  free  state  partially  emerged 
frcnn  the  many-layercil  cyst.  A  small  encysted  mass  is  seen  at  c  between  the  envelopes  of  the 
latter.  At  o  and  elsewhere  in  the  main  body  of  the  protoplasm,  as  well  as  in  outlying  portions, 
invested  food  particles  are  shown.  The  oat-shaped  corpuscles  are  seen  on  the  stiff  extended 
filaments,  x  about  150.  (From  Lankester,  after  Archer.)  1  and  3,  I.abi/rinthulrt  riteltiiw, 
C'ienk.  1,  a  colony  crawling  upon  an  alga.  The  units  are  partly  aggregated,  partly  extended 
on  the  network  of  stiff  extended  pseudopodia.  x  about  120.  3,  part  of  the  network,  x  about 
250.  At  p  and  p1  several  units  have  fused  into  a  common  mass  ;  »,  s,  units  which  have  assumed 
the  spherical  shape  and  are  stationary.  4-7,  Labyrinthula  macrocystis,  Cienk.  4,  a  single  unit 
giving  out  three  pseudopodia  ;  n,  its  nucleus  ;  x  320.  5,  a  group  of  encysted  units  invested  in 
a  tough  secretion,  x  about  250  ;  f>  and  7,  encysted  units  the  contents  of  which  have  divided 
into  I'our,  x  about  320.  (From  Lankester,  after  Cienkowski.) 

test.  Both  forms,  together  with  Labyrinthula  and  Chlamydomyxa,  may 
provisionally  be  regarded  as  related  in  one  direction  to  outlying  members 
of  the  Gromiidea,  here  included  in  the  Foraminifera,  and  in  others  to  the 
Heliozoa  and  the  Proteomyxa.  The  grounds  for  regarding  the  two  latter 
genera  as  especially  related  have  vanished  in  the  light  of  fuller  knowledge. 


1.  Cienkowski.     Ueber  den  Ban  u.  Entwickelung  der  Labyrinthnleen.     Arch. 

f.  inikr.  Anat.  Bd.  iii.  (1867),  p.  274. 

2.  Ueber  einige  Rhizopoden  und  vevwandten  Organismen.      Ibid.  Bd. 

xii.  (1876),  p.  44. 

3.  Lankester,  E.   II.     Article  "Protozoa"  (Class  Labyrinthulidae).     Encyclo- 

paedia Britannica,  1891. 

4.  Zopf,  jr.     Zur   Kenntniss   d.   Labyrintlmleen,  eine   Fain.   d.    Mycetozoen. 

Beitr.  zur  Phys.  u.  Morphologic  niederer  Organismen,  Heft  2  (1892), 
p.  36,  and  Heft  4  (1894),  p.  60.     Leipzig. 



THE  organisms  that  are  now  included  in  this  family  were  formerly 
regarded  as  Porifera,  and  several  of  them  were  described  in  1889  by 
Haeckel  in  the  "  Challenger  "  volume  xxiii.,  on  the  deep-sea  Keratosa.1  In 
the  year  1892,  Goes  (1)  described  "a  peculiar  arenaceous  Foraminifer 
from  the  American  tropical  Pacific"  as  Neusina  agassizii,  which  Hanitsch 
in  the  following  year  proved  to  be  identical  with  Haeckel's  deep-sea 
Keratose  sponge  Stannophyllum  zonarium.  We  are  indebted  to  Schultze 
(2)  for  an  exhaustive  treatise  on  these  genera,  and  the  more  definite 
proof  that  they  are  not  sponges,  but  probably  related  to  the  Foraminifera. 
They  are  spherical  or  disc-shaped  (Psammetta),  fan-shaped  (Stannojihyllum, 
Fig.  1),  or  dendritic  (Stannoma)  bodies  of  about  20  mm.,  more  or  less,  in 

diameter  or  height,  and  of  a  fibrous,  spongy 
texture.  They  have  been  found  at  depths 
of  from  550  fathoms  to  3000  fathoms  in 
the  Indian,  Atlantic,  and  Pacific  Oceans. 

They  consist  of  a  plexus  of  thin-walled 
tubes,  some  of  which  open  on  the  surface, 
and  the  meshes  of  the  plexus  contain  a 
large  number  of  foreign  bodies  (xenophya), 
such  as  the  shells  of  Radiolaria,  Foramin- 
ifera, spicules  of  sponges,  and  grains  of  sand. 
The  tubes  contain  either  a  large  number 
of  dark  olive-brown  bodies,  the  sterkomata, 
or  else  a  multinucleated  plasmodium  con- 
taining numerous  clear  solid  bodies  called 
the  granellae.  The  sterkomata  are  remark- 
ably resistant  to  strong  acids  and  alkalis,  and  they  often  contain  fragments 
of  radiolarian  and  foraminiferan  shells.  They  are  regarded  by  Schultze  as 
of  the  nature  of  the  faecal  balls  such  'as  are  found  in  other  Foraminifera 
(Gromia,  Saccamina,  etc.).  The  tubes  containing  the  sterkomata  (Ster- 
komarium)  are  probably  continuous  with  the  tubes  containing  the  granellae 
(granella'rium).  The  granellae  are  about  1-2  /x  in  diameter,  and  are  mainly 
composed  of  barium  sulphate.  The  nuclei  which  occur  in  the  plas- 
modium of  the  granellariurn  are  very  numerous,  and  usually  scattered 

FIG.  i.  " 

Stannophyllum  zonariiim,  Haeck. 
x  §.    (After  Schultze.) 

1  Cf.  A  Treatise  on  Zoology,  Part  II.,  1900,  p.  154. 



irregularly  among  the  granellae.     In  some  cases  (Fig.  3)  aggregations  of 
nuclei  with  an  investing  portion*  of  the  protoplasm  become  separated  from 


FIG.  2. 

Section  through  the  middle  layer  of  J'srnnminn  glubigfrina,  Haeckel,  showing  the  plexus  of 
tubes  containing  a  multinucleated  plasmodium.  At  o,  a  are  seen  some  of  the  foreign  bodies 
(xenophya)  associated  with  the  organism  ;  s,  s,  tubes  of  the  sterkoinarium ;  g,  g,  tubes  of  the 
granellarium.  (After  Schultze.) 

the  plasmodium,  and  these  break  up  into  swarm-spores,  which  Schultze 
regards  as  possibly  gametes. 

In  the  family  Stannomidae  there  are  found,  in  addition  to  the  tubes- 
already  mentioned,  many  fine  skeletal  fibres  called  the  "  linellae,"  which 
form  a  plexus  in  the  interstices  of  the  other 
parts  of  the  organisms. 

In  the  absence  of  any  information  con- 
cerning the  early  stages  of  development,  or 
of  the  character  of  the  pseudopodia  in  the 
members  of  this  family,  it  is  difficult  to 
assign  to  them  their  proper  systematic 
position.  The  Foraminiferan  genus  Poly- 
trema  and  some  of  its  allies  liave  the  same 
habit  of  incorporating  into  their  substances 
sponge  spicules  and  other  foreign  bodies,  and 
they  also  lose  at  an  early  stage  of  develop- 
ment the  external  evidence  of  the  chambered 
condition,  and  assume  dendritic  forms. 
Moreover,  in  Polytrema  we  find,  in  addition 

to    the    calcareous    skeleton,    a    system    of  are  breaking  up  into  spores, 
horny  or  chitinous  tubes  which  have  some 

resemblance  to  the  tubes  of  the  Xenophyophoridae.  In  the  absence  of  a 
calcareous  "skeleton  the  family  differs  from  all  the  higher  and  more 
differentiated  families  of  Foraminifera,  but  nevertheless  the  affinities  of 
the  family  are  greater  \vith  this  class  than  with  any  other  Protozoa. 

FIG.  3. 

Diagram  of  the  granellar  region- 
of  a  Xenophyophorid,  showing  the 
nuclei,  n,  n,  and  granellae,  g,  g,  of 


The  Xenophyoplioridae  may  therefore  provisionally  be  placed  in  the 
Class  Foraminifera. 


Sub-Family  PSAMMIXIDAH-.  Without  linellae.  Not  flexible.  Genera 
— Psammetta,  F.  E.  S.  ;  Psammina,  Haeck. ;  Cerelasma,  Haeck.  ;  Holo- 
psamma,  Carter  ;  Psammopemma,  Marshall. 

Sub-Family  STANNOMIDA.  With  linellae.  Body  flexible.  Genera — 
Stannoma,  Haeck.;  Stannophyllum,  Haeck.  (Fig.  1);  Stannarium,  Haeck. 


1.  Goes.     Ncusina  agassizi.     Bull.  Mus.  Harvard,  xxiii.,  1892,  p.  19f«. 

2.  Schultze,  F.  E.     Die  Xenophyophoren.     "  Valdivia"  ExpeJ.  xi.,  1905. 

3.  "Siboga"  Exped.  Mon.  iv.  bis,  1906. 

4.  Bull.  Mus.  Harvard,  li.  6,  1907. 


Figures  given  in  thick  type  refer  to  the  systematic  position. 
f.  refers  to  an  illustration. 

Abyla  pentagona,  249 
Acautharia,    94,    102,    106, 

113,  145 

Acanthochiasma,  146  ;  A. 
cruciala,  146  ;  A.  fusi- 
forme,  145  ;  A.  krohnii, 

145  ;  A.  rubescens,  143 
Acanthochiasmidae,  146 
Acanthocystis,  21,  24,  28, 

29,  34, 119  ;  A.aculeata, 

16/.,    27/.,  28/.  ;    A. 

italica,  34  ;  A .  marina, 

34  ;  A .  simplex,  34  ;  A . 

spinifera,   23  ;    A.    tnr- 

facea,  23 

Acanthodinium,  187 
Acanthometra  sicula,  143 
Acanthometrida,  113,  145 
Acanthometron,    123,  146  ; 

A.   bifidum,    137/.  ;   A. 

Claparedei,l05f. ;  A. pel- 

lucidum,  118/.,  146 
Acantfwnia,  146  ;  A.  ligur- 

ina,    146  ;    A.    miilleri, 

146  ;  A.  tetracopa,   127, 
128/.,  132/. 

A  cant/ion  id ium,    146  ;    ^4. 

echinoides,  146  ;  .4.  ^«Z- 

lidum,  146 
Acaiithoniidae,  146 
Acanthophractida,  146 
Acrasiae,  39 

.  lr.V".v/,9,    65 

Actineliida,  145 
Actinelius,    145  ;    .1.  ^'/'- 

pureus,  145 
Actinolophus,    15,   23,   28, 

Actinomma,  127  ;  .4.  as&r- 

acanthion,  103/. 
Actinomonas,  165 
Actinophrys,    18,    19,    21, 

29,  30,  33,  39  ;   vl.    soZ, 

15,  16/.,  21  f. 

Actinosphaeridium,  33 

Actinosphaerium,  21,  22, 
23,  25,  26/.,  29,  30,  32, 
33,48,86,  87;  .1.  arach- 
noideum,  23  ;  A.  Eich- 
horni,  14/.,  22  ;  A.  im- 
patiens,  10  f. 

Actissa,  104,  110,  144 

Aethalia,  56 

akaryote,  1,  2 

Alwisia,  63 

Amaurochaetaceae,  63 

Amaurochaete,  63  ;  -I.  ati-<>, 

Amaurochaetineae,  62 

Amaurosporales,  61 

Amoeba,  2,  69,  77  ;  A. 
binucleata,  73,  79  ;  A. 
buccalis,  84  ;  ^1.  crystal- 
ligera,  73,  78  ;  ^1.  dof- 
leini,  71  ;  ^1.  fluida, 
78;  ^1.  guttula,  78/.,79; 
yl.  hyalina,  73  ;  .4.  Aar- 
tulisi,  84  ;  ^4.  Umax,  69, 
70,  73,  77/.,  79,  83  ;  .4. 
pilosa,  68  ;  .4.  proteus, 
73,  74/.,  77,  78/.,  79  ; 
.4.  radiosa,  79  ;  -4.  rote- 
<on'a,  195  ;  ^4.  terricola, 
68  ;  .4.  urogenitalis,  84  ; 
^4.  verrucosa,  78f.;  A. 
villosa,  79  ;  .4.  vorax, 
78 /. 

yliftoeda  (marine  forms),  78 

Amoebophrya,  105  /.,  123 

Amoebulae  in  Heliozoa,  29  ; 
in  Lobosa,  76,  77  ;  in 
Mycetozoa,  42,  59 ;  in 
Proteomyxa,  4,  5 

A  iiijiliiiliniuui,  183 

Amphilonche,  123,  146  ; 
.1.  atlantica,  137/.  ;  .4. 
belonoides,  146  ;  Jl.  ww-s- 
sanensis,  103/. 


Amphilouchidae,  146 
Amphinwiias,  168 
Amphisolenia,     187  ;     -<4. 

globifera,  184/. 
Amphizonella,  80 
Ancyromonas,  165 
Anemineae,  55,  63 
Anisonema,  171 
Ankistrodesmus,  179 
Anopheles,  240  ;  ^4.  maculi- 

pennis,  248 
Antlwphysa,  158, 161,  167  ; 

-4.  vegetans,  178 f. 
Apheiidinm,  3, 10,  11 ;  ^4. 

lacerans,  11 
Aphrothoraca,  33 
Apiocystis,  180 
Apstein,  192 
Arachnula,  9 
.4rce/fo,  68,  71,  72, 85/., 86 

87,  90  ;  A.vulffaris,90f. 
Arcellidae,  85,  90 
Archer,  22,  274,  277,  279 
Arcyria,  52  n.,  55,  64,  65  ; 

.4.  incarnata,  56 f. ;  ^4. 

punicea,  56f. 
Arcyriaceae,  44,  55,  64 
Ascoglena,  157,  171 
Astasia,    171  ;    .4.    <e»ww^ 


Astasiina,  171 
Astrocapso,  146  ;  A.  coro- 

nata,  146;  ^4.  tritonis,I46 
*  1  strodiscv  his,       33;       .4 . 

radians,  16  /. 
Astrolophidae,  145 
Astrolophus,  145 
Astrosestrum  acanthastrum, 


!  Atliene  noctua,  202,  233 
Athias,  254,  269 
Atlanticella,  109,  150;    ^4. 

craspedota,  149 
Atractonema,  171 



Aulacantha,  113,  119,  121  ; 

Brass,  13 

Chactomorpha  crassa,  10 

A.  scolymantha,  111  /., 

Brauer,  31,  32,  35,  245 

Chalaro'thoraca,  23,  34 

112,     117,      121,     124, 

Braun,  13 

Challengeridae,  113,  148 

125  /.,  136,  147 

Brefeldia,  63 

Challengeron  armatum,  148 

Aulacanthidae,  147 

Breinl,  206  n. 

/.  ;  (J.  balfouri,  148  ;  C. 

A  ulactin  ium    actinastrum, 

Bruce,  195,  199,  269 

golfense,  148  ;  C.  johan- 

109  /. 

Brumpt,    196,     198,    204, 

nis,     148  ;    C.    trioden, 

Aulodendron  boreale,  148 

226,  228,  269 


A  idographiftfurcellata,  148  ; 

de  Bruyue,  4,  13 

Chilomonas,  176 

A.  tetrancistm,  148  ;  A. 

Buffard,  205,  269 

Chironomus  plumosus,  245 

zetesios,  148 

Burstdla,  3>  11,  12,  40,  60 

Chlamydococcus,  180 

Aulokleptcs  Jlosculus,  110, 

Biitschli,  5,  6  n.,  13,   35, 

Clilamydomonadina,  180 

135  /. 

39,  66,  70,  91,  115,  131, 

Chlamydomonas,   22,  180  ; 

Auloscena  vertidUatus,  112 

151,  190 

C.  pulvisculus,  166/. 

/.,  148 

Chlamydomyxa,    39,    274  ; 

A  ulosphaera  elegantissima, 

(J<«H<iiii  nii'fii,  148 

C.  labyrinthuloides,  274, 

105  /.  ;  A.fiexuosa,  148 

Calcariueae,  49,  55,  62 

275  /.,  279  /.,  282  /  ; 

Aulotractus  fusidus,  148 

Calkins,  G.  N.,  13,  20,  79, 

<  '.    Montana,    274,   277, 

Audcularia,  49 

91,  219 

278,  279  /. 

Awerinzew,  35,  91 

Calouemineae,  64 

Chlamydophora,  33 

Calymma,  95 

L'lilnrinJ.esmus,  158 

Badhamia,  52  n.,  55,  62  ; 

Calyptrosphaera,   176  ;    C. 

Chlorogonium,     180  ;      C. 

B.panicea,  42/.,  52  /.  ; 

oblonga,  175/. 

I'uchlorum,  166  /. 

B.  utricularis,  44  /.,  46 

Campascus,  90 

Chloromonadina,  174 

/.,  48,  49,  50/.,  51  /. 

Camptonema,  33 

CJwanocystis,  35 

Barbagallo,  B.,  92 

Cannocapsa,  146  ;  C.  oscu- 

Choanortagellata,  176 

cle  Bary,  38,  61,  66 

lata,  146 

Chodat,  22 

Basidiomycetes,  40 

Cannosphaera     antarctica, 

Chodatella,  179 

Bathybius,  12 


Chondrioderma,  53,  54,  55, 

Belonaspidae,  146 

capillitium,  52,  55 

62  ;  (7.  testaceum,  54  f. 

Beneden,  E.  van,  2,  13 

Carpocanium  diadema,  105 

Chondropus  virulis,  33 

Berg,  195 

/,  147 

Christophers,  257,  272 

Bicosoeca,    161,    168  ;     B. 

Carteria,  178,  180 

Chromatella,  80 

socialis,  158,  168 

Casagrandi,  Q.,  92 

Chromidia,  in  Heliozoa,  18  ; 

Bikoecina,  168 

Cash,  J.,  13,  78 

in  Lobosa,   71  ;  in  Pro- 

Billet,  226,  269 

Castauellidae,  150 

teomyxa,    1  ;    in   Radio- 

Biomyxa,  2,  3,  9  ;  B.  cometa, 

Castanidium  apsteini,  150 

laria,  121 

9  ;  B.  <cagans,  9 

Castellani,    A.,    92,    196, 

Chromomonadidea,  173 

Bionomics  in  Tlialassicolla, 


Chromulina,  157,  174;  C. 



•rosanojft,  173 

Blackmau,  180,  192 

Central  capsule  in  Eadio- 

Chrysamoeba,  173,  174 

Blepharisma,  22 

laria,  114 

Ohrysococcus,  161,  174 

Blepharocysta,  186,  187 

Centralkorn,  28 

Chrysomonadina,   174  ;    C. 

Boderia,   10  ;    B.   turneri, 

Centrochlamys,  80 

loricata,  174  ;   C.  mem- 

11  / 

Centropyxis,  71,  75,  76,  77, 

branata,  176  ;  C.    nuda, 

Bodo,  157,'  161,  162,  163, 

86,  87,  88,  89 


167,  246  ;    B.  caudatus, 

CepJuilothamnion,  161,  167 

Chrysopijxis,  174 

166  /.  ;  B.  lacertae,  211, 

Ceratiidae,  187 

Cienkowski,    on     Chlamy- 

247;  B.  lens,  178/. 

Ceratiomyxa,    40,    57,    59, 

-.  domyxa,  280  ;  on  Helio- 

Bodonina, 167 

64,  66  ;  C.  mucida,  58  f. 

zoa,  29,  35  ;  on  Labyrin- 

Borgert,     110,     119,    124, 

Ceratiomyxaceae,  64 

thula,  283  ;  on  Mastigo- 


Ceratium,   158,  186,  187  ; 

phora,  190  ;  on  Myceto- 

Botryocampe  inflata,  147 

C.  hirundinella,  183  n.  ; 

zoa,  38,  43,  61,  66  ;  on 

Botryococcus,  179 

C.  tripos,  186  /. 

Protozoa,   4,    10  /.,   13  ; 

Botryoidea,  147 

Ceratocorys  horrida,  184/., 

on  Racliolaria,  97,  152 

Bott,  91 


Cienkmvskia,  Heliozoa,  34  ; 

Bourne,  81,  91 

Oercobodo,  166  ;   C.  crassi- 

Mycetozoa,  62 

Box  boops,  247 

cauda,  166/. 

Ciliophrys,  4,  8,  10  /.  ;  C. 

Bradford,  206  n.,  269 

Cercomonas,  165 

infusionum,  10  f. 

Brandt,  96,  97,  104,   106, 

Ccrelasma,  286 

Cimex  rotundatus,  259 

110,  112,  127,  129,  152 

Certes,  273 

Circoporidae,  150 



Circoporus        sexfuscin  i's, 

112,  117 

Cistidium  inenne,  105  /. 
Cladomonas,  168 
Cladophora,  11 
(  'l«i<l  *  I*-,:  ,i  iuin      tricolpium, 

Cladothrix,  72  f.  ;  (7.  ^>eZo- 

myxae,  81 
Classification   of  Haemofla- 

gellates,  248  ;  of  Helio- 

zoa,   33  ;    of   Lobosa,  — 

Gymnamoebida,         77  ; 

Thecamoebida,    84  ;     of 

Mastigophora,    154  ;    of 

Myceto/.oa,    61  ;  of  Pro- 

tuoniyxa,  6  ;    of   Radio- 

laria,  144  ;  of  Xenophyo- 

phoridae,  286 
Clastoderma,  63 
Clathrocydas  craapedota, 

Clathrulina,   25,    29,    34  ; 

C.  elegans,  16/.,  23 
Closterium,  32 
Clypevlina,  90 
Coccolithoplioriuae,  176 
Coccolithqpora,    176  ;      C'. 

lejttopora,  175  f. 
coccolitlis,  174 
Cocliliopodiidae,  84,  85,  88 
Cochliopodium,  71,  80,  88  ; 

C.     actinophorum,     88  ; 

C.    diijitntuni,    88  ;     C. 

pellucidum,  S8/. 
Cochlodinium,  185 
Codonoeca,  167 
Codosiga,     177  ;     C.    um- 

bel la  ta,  178/. 
Coelodeudridae,  150 
Cododendron        ramosissi- 

mum,    150  ;   C.  gracilli- 

minn,  105  /. 
Coelographidae,  150 
Coelomoiuts,  174 

murrayanum  , 
151  /.  :  ''.  trtkmit,  151 
Coelothamn  us         davidoffi, 
151  /. 

Coenobia,  181 
Colacium,  171 
Coleochaeta,  11 
Collodaria,  113 
<'i>l/,,ilict)/on,  169 
Collosphaera,  111  w.,  121, 

12:;  ;  <_'.  )iii.r/,-i/i,  140/.  ; 

C.  murrayaitc,  145 
Collospbaeridae,  104,  145 
Collozoum,   98,  139  /.  ;  C. 

fill  rum,  138;  C.  inenne, 

103    /.,     126    /.,    138, 

141/.,  142  /.,  145;  C. 
.pelagicum,      145  ;       C'. 

radiosum,  138 
Colpodella,  3,  5,  10,  11  ; 

(7.  pugnax,  10/. 
Colponema,  168 
columella,  53 
Comatricha,     52  n.  ,      55, 


Concharidae,  150 
Contractile     vacuoles       in 

Heliozoa,  18  ;  in  Lobosa, 

85;     in     Mastigophora, 

160  ;  iu  Mycetozoa,  49  ; 

in    Proteomyxa,    3  ;    in 

Radiolaria,      absent     in 

Thalassicolla,  97 
Convoluta,    22  ;     O.     ros- 

co/ensis,  129,  180 
Copromonas,    160  /.,   161. 

162,  163,  171,  172,  177  ; 

C.  subtilis,  172 
Copromyxa,  65  ;  C.  protect, 

60  /. 

Cornutella  dathrata,  147 
Cornuvia,  64 
Cortina  typus,  107  /. 
Cwtiniscus  typicus,  146 
Corycia,  80,  89 
Costia,      157,      168  ;      C. 

necatrix,  169 
Craig,  C.  F.,  92 
Craspedomonadiua,  177  ;  C. 

loricata,  177 
Craspedotdla,  190 
Craterium,  44,  54,  55,  62  ; 

C.  pedunculatum,  54  /. 
Crawley,  23,  35 
(.'rilimria,  54,  63 
L'rithidiu,  228,  240,  241  /.  ; 

C.    campamdata,     245  ; 

C.  fasciculate,  242,  248 
Gryptoglena,  171 
Cryptoruonadina,  176 
('-in  nbalus  kochii,  249 
Cucurbitdla,  89 

I'ipiens,  202  f.,  233, 


Cyathomonas,  176 
Cydonexis  annularis,  158 
Oycloptems  lumpus,  247 
Cylindyospermum,  11 
Cyphoderia,  90 
Cyrtocalpis  obliqva,  147 
Cyrtoidea,  114,  147 
Cystoflagellata,  188 
Cytodadus    spinosus,    115 

/,  1*4 

,  179 
Dactylosjthaera,     79  ;     /). 

polypodies    72  /.,    73 ; 
/>.  radiosa,  78/.,  79 

l)n  in <> ida  reevesii,  254 
Bangeard,  P.  A.,  3,  13 
Danilewsky,  195,  255,  269 
Delage,  39 
Delap,  153 
Dendromonas,  158 
Desmothoraca,  23,  25,  34 
Diachaea,  62  ;  X>.  elegans, 


Dianema,  64 
Diaphorodon,  90 
Diatoms,  11 
Dictydiaethalium,  63 
Dictydium,     54,    63 ;    Z>. 

umbil ica him,  55  /. 
Dictyocephahis      ocellatvs, 


Dictyomyxa,  10 
Dictyophimus  clevei,  147 
Didyopodium,  127 
Dictyosteliaceae,  60,  65 
Bictyostdium,  60,  65 
Dictyota,  114 
Didymiaceae,  56,  62 
Didymium,  44,  55,  56,  62  ; 

Z).  di/orme,   43  /.  ;  Z>. 

effusuflf,  57 /. 
Difflugia,    71  /,    72,   84, 

85,  86,  89  ;  I>.  globosa, 

86;  D. pyriformis,  89 /. ; 

Z).  urceolata,  86,  87,  88 
Difflugiidae,  89 
Dimastigamoeba,  165 
Dimorpha,  164,  165 
Dinamoeba,  68,  80 
Dinema,  171 
Dinobryon,  157,  158,  161, 

173,  174  ;  Z>.  sertularia, 

1-65 /. 

Dinoflagellata,  182 
Dinophysidae,  187 
Diiiophysis,  187 
Diplocouidae,  146 
Diploconus,  146 
Diplomita,  168 
Diplophrys,        283  ;       Z). 

Archeri,   283 ;    Z».   ster- 

corea,  283  . 
Diplophysalis,  4,  5,  8 
Diplosiga,  177 
Discoidea,  145 
Discorbina,  112 
DiscospJiaera,      176 ;      Z>. 

tabifer,  175  f. 
Distephanits  speculum,  191 
Distigma,  171 
Distomatina,  169 
Dobell,  160  «.,  163,  172, 





Doflein,  F.,  13 

"Fingersand  Toes"  disease, 

Gymnosphaera,  23.  33 

Donovan,  256,  272 


Gyromonas,  169 

Dopter,  82,  92 

Flagellata    (Mastigophora), 

Dorataspidae,  146 


Hacker,  113,  117,  122,  153 

Dorataspis,  127 

flagellulae,  4,  5,  29 

Haeckel,   1,   13,  104,   110, 

Dourine,  196,  197,  206 

Flowers  of  Tan,  47 

119,  127,  131,  152,  284 

Dreyer,  116,  131,  152 

Forde,  196 

Ilaeckelina,  8 

Dum-dum  fever,  256 

Fowler,  113,  152 

Haematococcus,    180  ;     //. 

Durham,  H.,  240 

Franya,  254,  269 

palustris,  166  f. 

Dutton,  196,  255,  269 

Freuzel,  91 

Haemaiomonas,  250 

Frenzdina,  90 

Haematopinus,  198,  203 

Echinomma    leptodermum, 

Fuligo,  50,  55,  56,  57,  62, 

Haematopota.  242,  258 


65  ;    F.    septica,   40  /., 

Haemoflagellates,  193  ;  bio- 

Echinostelium, 63 

47,  57  /. 

logical       considerations, 

Ectobiella,  3/.,  12 

217  ;  classification,  248  ; 

Ehrenberg,    17,    112,    151, 

comparative  morphology, 


Gamble,  22,  35,   99,   110, 

207  ;       evolution       ami 

Eikenia,  80 

129,  153,  180,  192 

phylogeuy,  240  ;  habitat, 

Elaeorhanis,  14,  22,  23,  34 

Gametocytes,  25 

196  ;      historical,     194  ; 

Elaster,  35 

Gasteromycetes,  40 

Leishman  -  Donovan  - 

Elpatiewsky,  W.,  93  n. 

Gazdletta,  149 

Wright  bodies,  255  :  life- 

Enchylema,  69 

Geddes,  274,  280 

cycle,  226  ;  list  of  hosts, 

Endamoeba,    68,    71,    82  ; 

Giemsa,  196 

162  ;     literature,     268  ; 

E.    blattae,    74  /.,    83, 

Glaeocystis,  180 

multiplication,  222 

84  /.  ;  E.   coli,   73,   74, 

Glenodiniidae,  186 

Halistemm  a      tergestin  u  m  , 

75,  82  /.  ;  E.  histolytica, 

Glenodinium  cinctum,  184 


75,    82,  83/.  ;  E.  iurai, 

/.  ;  G.  pulvisculus,  187 

Halteridimn,  236,  248 

83  ;  E.  undulans,  83 

Gloidium,  2,  3,  5,  6/. 

Hanburies,  3 

Endosporeae,  40,  57 

Glossina,   200  ;    G.  fusca, 

Hauna,  270 

Endyonema,  2,  3,  5,  12 

199   n.,    200,    201;    G. 

Haplococcus,  3,  12 

Enerthenema,  62 

morsitans,  199;  G.patti- 

Harper,  65 

Engler,  191 

dipes,    199  n.  ;   G.  pal- 

Hartmaun,  159  «.,  192 

Enteridium,  63 

palis,  199,  200,  231  ;  G. 

Hartog,  E.,  13,  68 

Enteromyxa,  3,  12 

tachiiioides,  200 

Hedriocystis,  23.  34 

Entocanmda  hirsuta,  148 

Gluge,  195 

Hdcosoma  tropicum,  259 

Entosiphon,  171 

Goebel,  13 

Heleopera,  85,  90 

Esox  lucius,  255 

Goes,  284,  286 

Heliophrys,  33 

Estrdla,  33 

Goldschmidt,  R.,  91,  163, 

Hdiosphaera  inermis,103f. 

EucecrypJialus,  128 

164,  192 

Heliozoa,  14  ;  classification, 

Eucoronis  nephrospyris,  146 

GolenJdnia,  33,  179 

33  ;    food,    18  ;    karyo- 

Eucyrtidium,      127  ;      E. 

Gomphonema,  7 

kinesis,     25  ;    literature, 

cranioides,  108  f. 

Gonium,     158,     182  ;     G. 

35  ;    nucleus,     25  ;     re- 

Eudorina, 181,  182 

pectorale,  158,  166  /. 

production,  28  ;  skeletal 

Euglena,    157,    161,    171  ; 

Gonyaulax,  187 

investments,    23  ;  struc- 

E.    acus,    166   /.  ;    E, 

Grassia,  164 

ture,  15 

gracilis,  172  ;  E.  mridis, 

Gray,  199,  200,  203,  230, 

Hemiclepsis.  227 

166/.,  172 


Hemidinium,  183,  184 

Englenina,  171 

Greeff,  22,  24 

Hemitrichia,    55,    64  ;    H. 

Euglenoidea,  170 

Greenwood,  49,  66 

chrysospora,  56  f. 

Euglenopsis,  171 

Greig,  199 

Herouard,  39 

Eu-mycetozoa,  39 

Grenadier,  23,  28,  35 

Herpetomonas,    157,     161, 

Euplasmodida,  39,  40,  43 

Gruber,  78 

226,  240,  241,  250  ;  //. 

Euphysetta  natlwrsti,  148 

Gruby,  269 

biitschlii,     245    n.  ;    11. 

Eutreptia,  171 

Gubernaculum,  159,  194 

bombycis,  245  ;  H.  culicif, 

Evans,  G.,  195 

Quttulina,  60,  65 

242  ;    H.   gracilis,    241,- 

Exoeporeae,  40,  57,  64 

Guttuliuaceae,  65 

245  ;  //.  jaculum,  241  ; 

Exuviaella,       185  ;         E. 

Gynmamoebida,  77 

H.      lewisi,      195  ;      //. 

marina,  127 

Gymnococcus,  3,  5,  11 

minuta,  241  ;  H.  mnscae- 

jSfymnodinium,  183,  184 

domesticae,     232,     241  ; 

Famintzin,  58,  66,  98,  129, 

Gymnophrys,  2,   3,  9  ;  G. 

H.  sarcophagae,  245  ;  H. 


cometa,  10/. 

subulate,  241  /. 



Hertwig,   on  Heliozoa,   15, 

Jalin,  42,  65,  66 

Lebailly,  270 

24  /.,    25,    27,   31,    32, 

James,  272 

Lecquereusia,       89  ;       L. 

35  ;  on  Lobosa,  75,  87, 

Jenkinson,  280 

spiralis,  89  /. 

91  ;  on  Radiolaria,  114, 

Jennings,  70,  91 

Leeuwenhoek,  155 

115,  123,  127,  152 

Johnstone,  129,  153 

Leger,     196,     198,      215, 

Heterodevmaeeae,  63 

Jiirgeiis,  92 

217  n.,  226,   229,  230, 

',  187 

234,  240,  242,  245,  247, 

Heteromastigina,  248 

Kala-Azar,  256 

257  «.,  258,  270,  271 

Heteromastigoda,  167 

Karawiew,  123,  152 

Leidy,  23 

heteromastigote,  158 

Karyokinesis,     in     Actino- 

Leishman,  196,  257,  272 

Heterophrys,    21,    22,    28, 

sphaerium,25  ;  in  Lobosa, 

Leishmania  donovani,  232, 

34,   16-t  ;  //.   Fockei,  24 

73  ;     in     Mastigophora, 

256,  257  f.  ;  L.  tropica, 

/.  ;  //.  myriopwia,  16/., 

161     (Noctiluca,     190)  ; 

257  f.,  259 


in  Mycetozoa,  46/.,  48. 

Leishman-  Donovan-  Wright 

Hexacon  t  ium         entha  can- 

65  ;  in  Proteomyxa,    2  ; 

bodies,  255 

tli  in  in,   145;   //.  pachy- 

in Radiolaria,  126  ;  in  a 

Leocarjivs,  62 

derm  itm,  145 

Trvpanosome,  213 

Lcpidoderma,    56,   62  ;    L. 

Hexacoiixs,  146 

Keeble,    22,   35,    99,   110, 

tigrinmim,  54  f. 

Hexadon's  ICH-CHU*.  145 

129,  153,  180,  192 

Lepocindis,  171 

Hexalaspidae,  146 

Kempner,  198,  272 

Leptodiscns,  190 

Hexalonche      philosophical,- 

Kent,  195 

Leptomonas,  165 


Ken  ten,  172 

Leptophrys,  2,  3,  4  /".,  5,  8 

ins,  157,  162,  169  ; 

Keysselitz,  198,  229,  270 

Lesage,  82,  92 

//.  !,(ftatus,  178  /.  ;  H. 

Klebahn,  35 

Lesser,  15,  24  /. 

muris,  170 

Klebs,  127,  153,  161,  165, 

Lethodiscus        microporus, 

Hexaplagia  arctica,  147 



Hickson,  162,  192,  194  n. 

Koch,  200,    203,    251    n., 

Lenciscus       erythvoplithal- 

Hieronymns,  274,  276,  280 


mxs,  249 

Hinde,  153 

Kofoid,  182,  187,  192 

Lewis,  195 

liip-paraplegia,  206 

Kranzlin,  65 

Ley  den,  91 

Hippobosca  rufipes,  1  99  /. 

Krohn,  188  n. 

Leydenia,   84  ;    L.  gemmi- 

Hirmidium,  158,  177 

Krukenberg,  50,  66 

para,  84 

Histioneis,   188  ;   //.   cym- 

Krzysztalowicz,  273 

/./'•'•//,  63  ;  /..  i>nxilla,  56 

bcdaria,  184/. 

Liceaceae,  63 

Hoffmann,  273 

Labyrinthula,      39,      276, 

Lieberkiihn,  84 

Holmes,  '206  n. 

280  ;      L.      cienk«n:<l.-ii, 

Life-history     of     Chlamy- 

Holomastigoda,  164 

280  ;      L.     macrocystis, 

domyxa,  274  ;  of  Haemo- 

holomastigote, 158 

'-•  280,  282/.  ;  L.  vilellina, 

flagellates,  226  ;  of  Helio- 

IliJn/i~tii;nm((, 286 

129,  280,  282  /. 

zoa,  15  ;  of  Lobosa,  75  ; 

Homokaryota,  68 

Labyrintlmleae,  39 

of    Mastigophora,     155, 

Hoogenraad,  13 

Lachnobohts,  64 

162,  164,  172,  180,  189; 

Hosts  of  Haemoflagellates, 

Lamblia  intestinodis,  170 

of    Mycetozoa,    40,    58, 

list  of,  262-268 

I.iiiii/io.rniit!ui/iii      ninrmy- 

."'.i  ;  of  Proteomyxa,  3  ; 

Huxley,  151 

anum,  144 

of  Radiolaria,  104,  111 

Hycdobryon,  157,  158,  174 

Lamproderma,  62 

Lignii-res,  218  n.,  219,  271 

Hyalodiscns,  80 

Lamprosporales,  63 

lime-knots,  55 

lhi<ti<,li<,fl]if.  34 

Lang,  A.,  13 

Liit/Hi/fii/i/i,  63 

IIi/il,unn,  40 

Lankester,      on      Chlamy- 

Lingard,  271 

lliiilriii-l'ni'rn*       capybara, 

domyxa,  274,   277,  280  ; 

Linf/lij/a,  2,  8 


onHaemoflagellates,  195, 

liniii,  18 

Hydrodictyon,  179 

270  ;    on    Heliozoa.    17, 

Lister,  A.,  61,  67 

Hydrnrna,  176 

36;     on     Ijiliirintlmla., 

Literature,    of    Chlamydo- 

'inonas,  161,  176 

283  ;    on    Lobosa,     80  ; 

'inii-i'ii,  279  ;  of  Hsemofla- 

hypnocysts,  4 

on  Mastigophora,  158  ».,' 

gellates,  268  ;  of  Heliozoa, 

liypothallus,  54 

162,   168  H.  :  on   .Myce- 

35 ;     of    La  bi/riji  tl  nln. 

tozoa,  67  ;  pu  Radiolaria, 

'  283  ;  of  Lobosa,  91  ;   of 

Ji/iiii-Ju-ii/in'tlt'c.,  71 


Mastigophora,    191  ;    of 

Ijima,  91 

Larcoidea,  145 

Mycetozoa,  66  ;   of  Pro- 

Immermaun, 110,  153 

Laveran,  196,  204,  206  7?., 

teomyxa,  13  ;   of  Radio- 

Ineffigiata, 179 

207,   218  n.,   245.  252, 

laria,  151  ;  ofXenophyo- 

isomastigote,  158 

268,  270,  272,  273 

jilioridae,  286 



Lithamoeba,  80  ;  L.  discus, 

Mikroyromia,  39,  281 

18  ;  iu  Actinosphaerium, 

80  /. 

Miuchin,  159  n.,  192,  196, 

25,32;  in  Labyrin  tlmln, 

Lithelius  arborescens,  145  ; 

199,  200,  201,   203  n., 

280  ;  in  Lobosa,  70,  86  ; 

L.  minor,  145 

230,  231,  233,  246,  271 

in  Mastigophora,  161  ;  in 

Lithocircus  annular  is,  105 

Mitrophauow,  195,  271 

Mycetozoa,    48,    59  ;    in 

/.,  146 

Monadiua,  38,  248 

Proteomyxa,  2  ;  in  Radio- 

Lithocolla,  34 

Monadineae,  5,  6  n. 

laria,  94,  107,  110,  120 

Lithogromia  silicea,  148 

Monadopsis,  8 

Litholophus,  111 

Monas,  166,  167 

Oat-shaped  corpuscles,  39, 

Lithomelissa   setosa,    147  ; 

Monera,  1 


L.  thoracites,  147 

Monobia,  3,  5/.,  6,  15 

Ochromonas,  157,  174 

Litlwspluierella,  34 

Monocercomonas,  169 

Oedogonium,  8 

Lobosa,  68  ;  ehromidia,  71  ; 

Monolabis,  22 

Oicomonas,    157,    165  ;    0. 

classification,  77  ;  litera- 

Monomastigoda, 165 

mutabilis,    166  /.  ;     0. 

ture,  91  ;    nucleus,   70  ; 

Monomastigote,  158 

termo,  166/. 

reproduction,  72 

Monomastix,  159,  170 

Oligonema,  64 

Lohmami,  174,  192 

Monophyes  gracilis,  249 

Olive,  60,  66,  67 

Lophomonadina,  170 

Monopodittm,  8 

Oread  el  la,  63 

Lophomonas    blattarum, 

Monopylaria,  103,  107 

Ornithocercus,    186,    187  ; 

178  /. 

Monostomatina,  169 

0.  magnificus,  184  f. 

Lotsy,  192 

Monticelli,  13 

Orosphaera,  122,  144 

Liihe,  245,  247,  268 

Moore,  159  n.,  192,  206  n. 

Orosphaeridae,  144 

Lycogala,  56,  64 

Mucorinae,  40 

Ostenfeld,  36 

Lycogalaceae,  64 

Mugliston,  T.  C.,  93 

Ouramoeba,  78/.,  79 

Miiller,  Johannes,  131,  151 

Oxyrrhis,     163     n.,     168, 

Mallomonas,  161,  176 

Multicilia,  160,  163,  164; 


Margarita,  64 

M.  lacustris,  164 

Oxytoxum,  187 

Margaritaceae,  64 

Murray,  J.,  13,  113,  192 

Martini,  91 

Murrayella,  187 

Palmella,  180 

Mastigamoeba,    160,    164; 

Musgrave,  W.  E.,  93 

Palmella     stage     in     Zoo- 

M.  schulzei,  164 

Mycetozoa,  37  ;    classifica- 

xanthellae, 98  ;  in  Flagel- 

Mastigella, 156,  163,  164, 

tion,  61  ;  life-cycle,  42  ; 

lates,  156 

177  ;  M.  i-itraea,159f., 

literature,  66 

Palmodactylon,  180 

164  /.  ;  M.  vitrina,  164 

Myxastrum,  3,  5,  8 

Palmodictyon  ,  180 

Mastigina,  160,  164  ;  M. 

Myxodictyum,  11 

Pandorina,  182 

setosa,  164 

Myxodiscus   crystalligerus, 

Pantostomatiua,  164 

Mastigophora,      11,     155  ; 


Paramastigoda,  167 

classification,  163  ;  habit, 

Myxosphaera  coerulea,  140 

paraniastigote,  158 

157  ;     literature,     191  ; 

Pi'.miiieciiiiit,    20  ;    P.  cos- 

nucleus,  161  ;  nutrition, 

Nabarro,  199,  252 

tatum,   195  ;   P.    lorica- 

157  ;  structure,  158 

Nadinella,  90 

tum,  195 

Maupas,  20 

Nagana,  195,  197,  198 

Paramoeba,  79;  P.  eUhardi, 

Maupasia,  159,  170 

Nassellaria,  107,  113,  114 

70  /.,   73,    75,   79,   83; 

Mayer,  195 

Nationaletta,  149 

P.  hominis,  79,  83 

M'Neal,  217,  218  n.,  223, 

Nawaschiu,  11,  13 

Paramoecoides,  250 

227,  240,  242,  244,  245, 

Nebela,  85,  87,  90 

Paranema,  171  ;  /'.  trlcho- 

253,  271 

nebenkorper,  70 

phorum,  166/. 

Medusetta  tiara,  148 

Nepveu,  196 

Paranemina,  171 

Medusettidae,  148 

Neresheimer,  71,  91 

Parmulina,  89 

Megastoma,  157,  169;  M. 

Neusina  agassizii,  284 

Patton,  242,  259,  271,  273 

entericum,  169 

Noctiluca,  162,    188,  190  ; 

Pediastrum,  179 

Menoidium,  171 

N,  miliaris,  161  /.,  189 

Pelomyxa,  2,  68,  70/.,  71, 

Mereschkowsky,  13 

/.,  190  /.,  191  /. 

73,    75,   76  /.,   si  ;   P. 

Mesenteries,  44 

Novy,  200  n.,  217,  218  n., 

palustris,   72  /.,   76  ./'., 

Mesnil,  91,  196,  204,  206, 

227,  239,  240,  242,  244, 

81  /.  ;   P.  penanU.   81  ; 

207,  218  n.,   245,  252, 

245,  253,  271 

P.villosa,Bl;  I',  viridis. 

272,  273 

Nudearia,  8,  9,  14,  15,  23, 


Mesoscena,  114 

33  ;  N.  ddicntula,  10/. 

Penard,  E.,  13,  22,  23,  33, 

Metschnikoff,  50,  67 

Nuclei  in    Chlanu/domyxn, 

36,  39,  67,  91,  274,  277, 

microcysts,  42 

274  ;  in  Haemotta^ellates, 

278,  280 

Microglena,  161,  176 

194,  212  ;   in    Heliozoa, 

Penardia,  3,  9 



Perichaena,  64 

Plate,  190 

Protogenes,  5,  9  ;  P.  jtriin- 

Peridiniaceae,  185 

Platnaspis,  146 

ordialis,  9/. 

Prridinium,   186    187  ;  P. 

Platoion,  90 

Protomastigiua,  165 

dicergens,  186  /. 

Platydorina,  158,  182  ;  P. 

Protomonas,    11,    60  ;    P. 

Peripylaria,  102 

caudata,  182/. 

amyli,  38  ;  P.paroaitii-n, 

Perrin,  273 

Platytheca,  167 


Petalomonas,  171 

Plectellaria,  147 

Protomyza,  3,  4,  7/1,  11  ; 

Pliaeoconchia,  150 

Plectoidea,  147 

P.  parasitica,  10  /. 

Phaeocy.stina,  147 

Plectophora      arachnoides, 

Prototrichia,  64 

Phaeodaria,  108,  113 

147  ;  P.  novena,  147 

von  Prowazek,  on  Haemo- 

Phaeogromia,  148 

Plehn,  271 

flagellates,  198,  205,212, 

Phaeosphaera,  176 

Plenge,  42,  67 

223,    229,  231  M.,  232, 

Pliaeosphaeria,  148 

Pleodorina,  181,  182  ;    P. 

257  71.,  271  ;  on  Helio- 

Phalaeroma, 188 

illinoisensis,  183  f. 

zoa,     35  ;     on    Mastigo- 

Phalansteriina,  177 

Pleurococcus,  179 

phora,  159  H.,  163,  192  ; 

Barium,  158,  163«.. 

Pleuromonas,  167 

on  Proteomyxa,  4  w. 

177  ;  P.  consociatum,  166 

Plimmer,  206  ?i.,  269 

Prunocai-pi's  d'.<tn,-a,  145 

/.  ;  P.  volvocis,  168 

Podolampas,  187 

Pmnoidea,  145 

Pkarynyella  gastrula,  148 

Polykrikos,  185 

Prunophracta,  146 

Plwrmobotrys  hexathalom  iu, 

Polymastigiiia,  169 

Psammeftn,  286 


polymastigote,  158 

/'^rt?;!  »;  //ia      gldbigerina, 

Phorl  iciu  m  pylon  in  m,  145 

Polyoeca,  177 


Phractopeltidae,  146 

Polyplagia  novenuria,  147 

Psammini<Ii/c,  286 

Phryganella,  90 

Polyporus,  40 

Psamr/uijie/nmii,  286 

Phyllomitus,  167 

Polysphondylium,  60,  65  ; 

Pseudamphimonas,  11,  12 

Phyllomonas,  167 

A  violaceum,  60/. 

Pseudochlamys,  89 

Phyllostaurus,      146  ;     P. 

Polytoma,  177  ;  P.  nvella, 

Pseudodijfluyia,  90 

<[U<n!  rifolius,  146 


Pseudopodia,  of   Heliozoa, 

Physaraceae,  56,  62 

Pompholyxophrys,   22,  24, 

23  ;   of  Lobosa,    85  ;   of 

Physarella,  62 


Mastigophora,    160  ;    of 

Physarum,  52  ?;.,  55,   62  ; 

Pontigutasia,89  ;  P.  incisa, 

Proteomyxa,  3;  of  Radio- 

P.  mutans,  54  f. 


laria,  96,  106 

Physematiidae,  104,  144 

Pontobdella,      204,       224, 

Pseudospora,  3,  5,  8,  163 

Physematium,      121  ;     P. 


Pseudosi><>ri<?him,  10,  12 

niiiUcri,  144 

Pontomyxa,    9  ;    P.  Jtaca, 

Ptychodisfidao,  187 

J'hysomonas,  167 

9  ;  P.  pcdlida,  9 

PtycKo&iscus  nocticula,  187 

Phytheliii-ft,  33 

Pontosphaera,     176  ;      /'. 

pulsellum,  158  H. 

PhytoHagellata,  177 

haeckelii,  175/. 

Putter,  98,  153 

P  inaciophora,  24,  34 

Popowsky,  136,  153 

'•'•H/H'iias    (=J'yra- 

Pinacocystis,  21,  24,  34 

Porocapsa,  146  ;  P.    wittr- 

mimonas),  179,  180 

Piroplasma,  256  ;  P.  <2ouo- 

rayana,  146 

Pi/riil>}ui,-nxl  187 

Ewnt,  243,  257  /.,  259 

Poroapathidae,  148 

/'//  >  iilicuia,  91 

Playiacantka   arachnoides, 

Poteat,  \V.,  91 


Poteriodendron,  158,    161, 

Quadrula,  84,  85,  89  ;  <,>. 

Plagiocarpa       procyrtella, 


'/ulin'is,  84 


Pouchetia.  185 

Quatrefages,  189 

Plagoniscus       tripodiscus, 

I'm,  if  I,  192 


Pricolo,  171 

Rabinowitscli,  198,  272 

Planktonetta        attantica, 

Proales,  23 

Radiolaria,  94  ;  bionomics, 

120/.,  149  /. 

Prorocentraceae,  185 

96  ;  central  capsule,  114  ; 

Plasmodiocarps,  56 

Protamoeba,  2,  5,  6 

classification,  144  ;  cyto- 

Plasmodiopfwra, 2,  3,  4  «., 

Proteomyxa,  1 

plasm,  116  ;  distribution, 

5,  11 

I'roterosponyia,  158,  177  ; 

112;  food,  97;  literatim-, 

Plasmodium,    in   Labyrin- 

P.  haeckelii,  178  f. 

151  ;  nucleus,  120  ;  repro- 

fh/'/fi,  282  ;   in  Lobosa, 

I*r/>tn!Kithybiiis,  12 

duction,    136  ;    skeleton, 

72  ;    in    Mycetozoa,  43, 

Protocerativ.m,  187 

130  ;  variation  in,  110  ; 

57  ;  in  Proteomyxa,3 

Protococctis,  180 

yellow  cells,  126 

plasson,  2 

Protocystis  harstoni,   148  ; 

Raphi'l.iiiiK'iitix,  174 

plastogamic       fusion,       in 

P.  tridens,  148  ;  P.   <ri- 

Reinak,  195 

Heliozoa,  19;  in  Lobosa, 

/o/(/x.  148  ;  P.xiphmhn, 

Reproduction,    in    Chlamy- 



domyxa,    275  ;    in    Hae- 



moflagellates,     222  ;     in 

Schneider,  5/.,  13,  31,  32, 

Stannoma,  284,  286 

Heliozoa,     19,    28  ;     in 

205,  269 

Stanuoniitla,  286 

Lobosa,    72  ;    in    Masti- 

Schroder,  122,  153 

StannophyUum,  284,  286  ; 

gophora,    156  ;    in    My- 

Sclmberg,  A.,  92 

S.  zonarium,  284  f. 

cetozoa,   41  ;    in   Proteo- 

Schubotz,  92 

Statham,  257,  272 

myxa,  4  ;  in  Racliolaria, 

Schultze,  285,  286 

Steel,  195 

99,  136 

Schiitt,  187,  192 

Stegomyia,  240 

Reticularia,  52  n.,  56,  64  ; 

Sclerotiuin,  44,  50 

Steiniella,  187 

R.  lycoperdon,  42/. 

Scyphosphaem,     176  ;     S. 

Stemonitaceae,  53,  62 

Reticulariaceae,  63 

apsteini,  175./'. 

Stemonitis,   62  ;    S.  ferrii' 

rhabdoliths,  174 

Scytomonas,  171 

ginea,  55  /.  ;    S.  fusca, 

Rhabdomonas,  171 

Selenastrnm,  179 

41  /.,  57  ;  S.  splendens. 

Rkabdosphaera,  176 

Seim,  192,  212,  272 

55  f. 

Rlwphidiophrys,    22,     24, 

Sergcnt,  196,  226,  272 

Stephanosphaera,  158,  182 

28,  34  ;  R.  elegans,  35  /.  ; 

Siedlecki,  273 

Stephoidea,  147 

R.    pallida,    16  /.  ;    R. 

Siphonosphaera,  121,  123 

Stereum,  49 

viridis,  22,  23 

Siphoptychium,  63 

Sterromonas,  167 

Rlutpkidocystis,  24,  34 

Smith,  31,  36 

Stichogloea,  176 

Rhipidodeiidron,  158,  168 

Sorokin,  13 

Stole,  A.,  92 

Rhizomastigoda,  164 

Sorophora,  39,  59,  65 

Stomoxys  calcitrans,  199  /. 

Rhizoplasma,  9 

Sphaerastmm,  28,  34 

Strasbnrger,  52  n.,  67 

Rhizoplegma  boreale,  145 

Sphaerella,   179,   180  ;    S. 

Streptomonat,  168 

Rhunibler,  5,  6  n.,  13,  70, 

jacdustris,  166/. 

Stuhlmann,  200,  203,  216, 

85,  91 

Sphaerellaria,     106,     113, 

230,  231,  272 

Rhynchomonas,  168 


Stylamoeba,  80 

Robertson,  163,  169,    192, 

Kphaerocapsa,      146  ;       <S. 

Stylochrysalis,  157,  163  n., 

204,  214  n.,  216  n.,  224, 

c-niciata,  146 


228,  229,  272 

Sphaerocapsidae,  146 

Swingle,  225  n.  ,  272 

Rogers,  226,  257,  272,  273 

Sphaerocystis,      180  ;       S. 

Symbiotic  Algae   (Peridin- 

Romanowsky,  196 

Schroteri,  22 

'  ians),  94 

Roubaud,  203  n.,  231  n. 

SpJiaeroeca,  158,  177 

Syncrypta,   173,    176  ;    S, 

Ross,  240,  242,  272 

Sphaeroidea,  145 

voh-ox,  166/. 

Jiitppia,  3 

Sphaerophracta,  146 

Synura,  157/161,  176 

Sphaeropylidea,  145 

Syracoaphaera,  176 

Sphaerozoa,  102,  104,  145 

Syracosphaerinae,  176 

Sagena  ternaria,  148 

Sphaerozoidac,  104,  145 

Migenoarium,  148 

Sphaerozoum  neapolitanum, 

Sagospkaera  trigonilla,  148 

138,  141/.  ;  S.  ovodimare, 

Tabanus,  242  ;   T.  lineola, 

Sagosphaeridae,  148 


199  /. 

Salpingoecct,  161,  177;  S. 

Spkenomonas,  171 

Tansley,  180,  192 

fusiformis,    178  /.;    S. 

Spirilla,  195 

Tanypu-s,  245 

urceolata,  178/. 

Spirochaeta  evansi,  195 

Tetramitus,  157,   169  ;    T. 

Saltonella,  80 

Spirodinium,  183,  185 

rostratus,  178  f.  ;  T.  sul* 

Saunders,  49 

Spirogyra,  7,  8,  32 

catus,  178  f. 

Schaudinn,    on    Haemofla- 

Spiroidea,  147 

Tetramyxa,  2,  3,  11 

gellates,    196,  198,   202, 

Spironema,  170 

Tetraspora,  180 

205,  212,  217,  226,  235, 

Spirula,  11 

Thalassicolla,  94,  113,  114, 

241  n.  ,  248  n.,  258,  272, 

Spongodisms  favus,  145 

123  ;  T.pelagica,  95  /.  j 

273  ;    on   Heliozoa,    27, 

Spongomonas,  168 

T.    pellucida,    144;    T. 

29,     32,     34,    36  ;      on 

Spongosphaera  streptacan- 

nitcleata,  98,  99,  101/., 

Lobosa,  70,  75,  87,  88, 

tha,  105/. 

103/.,  144;  T.spumida, 

92  ;     on     Mastigophora, 

Sporangia,  50 


163,    192;     on    Proteo- 

Spores  in  Mycetozoa,   53  ; 

Thalassicollidae,  104,  144 

myxa,   6  n.  ;  on  Radio- 

in  Proteomyxa,  4 

Th  alassiosolen     atlant  icns, 

laria,  153 

Sporophore,  58 


Scheel,  74,  92 

Spumaria,  56,  57,  62  ;    S. 

Thalassolampe,     121  ;     T. 

Schewiakoff,  118,  131,  153 

alba,  54/. 

margarodes,  144 

Schizochlamys,  180 

Spumellaria,  113 

Thalassophysa,     120  ;      T, 

Schizogenes,  12 

Staborgan,  188 

papillosa,  144  ;  T.  pel  a* 

Schleiincysten,  232 

Stahl,  61,  67 

gica,    138  /.,    144  ;     T. 

Schleppgeissel,  194,  218 

Stannariiim,  286 

sanguinolenta,     128   f.  , 



138  /.,  144  ;    T.   ,^/<v- 

247,    249  ;    71.    iwrttaa, 

ii.rimn,   195  /.,  254  ;  T. 

losa,  138/. 


scyllii,  204,  255  /.  ;  T. 

Thalassophysidae,  104,  144 

Tn/j>anoscmia,     157,     163, 

soleae,  210  /.,  217  ;    T. 

Thalassothamnidae,  144 

168,  177,   248,  250  ;  T. 

theileri,     199    /.,     209, 

Thalassothamnus,   122  f.  ; 

ai'iKM,  208/.,  217,  253  ; 

251   n.,   253  ;  T.   tmns- 

T.  ramosus,  144 

T.  ba-rbdtulae,  215,  227, 

vaaliense,  216,  253  ;  T. 

Thecamoebida,  68,  84 

228,  230  ;  T.  boneti,  254  ; 

ugandense,  252  ;  T.  tai- 

Theoconus  ariadnes,  147 

T.   brucii,   195,    199  /., 

dulans,  255  ;  T.  mriuiii, 

Thiroux,  218  «.,  239,  272 

200,    201,    203,    208  /., 

227  ;  T.  ziemanni,  205, 

Thread  -plasmodium,      39, 

209,  214,  215,  216,  217, 

208  /.,  233,  237  /.,  238, 


220  /.,   221  /.,    223  /., 


Todd,  255 

231,    233  ;    T.   carassii, 

Trypaiiosomatidae,  248 

Topfer,  237  u. 

255  ;     T.    cobitis,    255  ; 

Trypanosomes,  193,  213  f. 

Topsent,  13 

T.    costatum,     254  ;     T. 

Trypanozoon,  248 

Torrey,  237  n. 

damoniae,  208  /.,   254  ; 

Tsetse-fly,  196,  201  n. 

Ti-achelomonas,  161,  171 

T.  danilewskyi,  204  ;  T. 

Tubulina,  63  ;  T.  stipitata. 

tractellum,  158  n. 

dimorphon,      253  ;       T. 


Trepomonas,  169 

duttoni,  205  ;  T.  elegans, 

Tubulinaceae,  63 

Trepospyris        corliniscus, 

255  ;  T.  elmassiani,  253  ; 

Tulloch,    199,    200,    203, 

107  /. 

T.  equinum,  197,  199/., 


Trichamphorn,  62 

205,  208  /.,  217,  220  /., 

Tuscarora  national  is,    122 

Trichia,    52    n.,     64  ;    T. 

221  /.,   224  /.,  251  /., 

/.,  150  /. 

fallax,    52   n.,    53  ;    T. 

253  ;      T.      equiperdum, 

Tuscaroridae,  150 

varia,  53/.,  56  / 

197    n.,    205   /.,     209, 

Tiiscarvsa  globosa,  150/. 

Trichiaceae,  44,  55,  64 

224  /.,   251  /.,  253;  T. 

Trichoinastix,  157,  169 

evansi,   199  /.,  253  ;  T. 

Trichomonas,     157,     160, 

flesi,  255  ;  T.  gambiense, 

Ulothri.c,  156 

162,169  ;  T.  intestutoltg. 

196,   197  n.,   199,  200, 

Ulotrichaceae,  156 


203,  208  /.,  220  /.,  221 

Umbilicosphaera,  176 

Trichosphaerium,    22,    68, 

/.,  230,   251  /.,  252;  T. 

Undwliiia,  250 

72,  73,  75,  80,  102,  127 

granulosum,    204,     209, 

Urceolus,  171 

Ti-i'J/'i.-tyopus,  115  ;  T.  efe- 

210  /.,    228,     255;    T. 

Uroglena,   158,  173,  176  ; 

<?«««,  147 

grayi,  200  n.,  201,  215, 

U.  ranarum,  106  /.,  194 

Trigonomonas,  169 

216/..224/.,  231,  232/., 

/.,  195,  254  ;   U.  wlvox, 

Trimastigina,  169 

233,  245,  246,  251  ;  T. 


Trimastix,  169 

liannae,  208/.,  209,  216, 

Urophagii-s,  169 

Triposolema,  188 

253,    254  ;    T.    inopina- 

Tripylaria,  102,  108.  147 

fi'ni,  210  /.,   216,   255  ; 

Trochiscia,  179 

T.    johnstoni,     214     «., 

Vacuolaria,  174 

Trochodiscus       ech  in  /*••//..,•, 

253  /.,  254  ;    T.  karyo- 

Vahlkampf,  70,  92 

145  ;  T7.  heliodes,  145 

zeukton,     210    /.,     212, 

Valentin,  194 

Trophochromidia,  71 

255  ;  T.  lewisi,  197,  198, 

Vampyrdla,  2,  3,  4/.,  5, 

Trophonucleus,  214 

203,   204,    205,    207  /., 

7/.,  15,  33 

Tropidoscyphus,  171 

208  /.,  210,  211  f.,  214, 

Vampyrellidium,  2,  3,  8 

TruncatidincT,  112 

216,  217,    219  /.,   222, 

Veley,  71,  81,  92 

Trypanomonas,  250 

225   /.,    226  /.,     229, 

Vernon,  98,  152 

•"Hiorpfia,  167,  198, 

251   n.,   252  ;  T.   mega, 

Verworn,  13,  95,  152 

238,  248 

212,    255;     T.    nanum, 

Voges,  272 

Trypanomorphidae,       167, 

209  ;    T.    ndspruitense, 

Volvociua,  181 


210  /.,  255  ;  T.  noctuae, 

Volvox,     158,     181  ;       V. 

Trypanqphis,     168,      209, 

198,   202,    205,  208  /., 

aureus,  182  ;  V.  globator, 

211,  213,  216,  249;  71. 

213,    218,    219  /.,  223, 

166  /.,   181  ;    V.  minor, 

grobbeni,    211,     249   /., 

233,  242,  243,  247,  248  ; 

166/.  ;   V.  tertius,  182 


T.     paddae,     253  ;     T. 

Trypanoplasma,   168,  209, 

polyflectri,  209  ;  T.  raiae, 

211,  217,249;  T.borreli, 

204,  209,  216,  224,  228, 

Wagnerdla,  34 

210  /.,  211,  215  /.,  216, 

231,  255  /.  ;   T.  remaki, 

Wasielewsky,  212.  272 

217,    249;    T.    cjjprini, 

204,    209,  210  /.,  216  ; 

Watase,  189 

210  /.,     211,    249  ;    T7. 

T.  rotatorium,  208,  209, 

Weuyon,  192 

intestincdis,     247,     249, 

210  /.,     216,     248    «., 

West,     G.     S.,     13,     36, 

250  /.  ;     T.     rentriculi, 

250  n.,  254  ;  T.  sangulnis 



Wolfenden,  113,  152 
Woodcock,  193  n.,  268 
Woronin,    3,    13,   58,    66, 

173,  192 
Wright,  S.,  13,  256,  273 

Xanthellae,  22 


Xiphicantha     (date,     128, 
142 /.,  143 

Zederbauer,  192 
Zoochlorella  act  in  osph  aerii, 

Zoospores,     in     Mycetozoa, 

40  ;  in  Proteomyxa,  4 
Zooteirea,  33 

zooxanthellae,     in     Radio- 

laria,  97 
Zopf,  2,   5,  6  n.,    13,    39, 

60,    61,   67,    280,    281, 


Zuelzer,  71,  86,  87,  92 
Zygacantha,  146  ;   Z.   sep- 

tentrionalis,  146 
Zygoselmis,  171 

Printed  by  R.  &  R.  CI.ARK,  LIMITED,  Edinburgh.